Use the images to explain why carbon forms a bond with four chlorine atoms.

Answer:

65 L is the volume of CO required

Explanation:

This is the reaction:

2CO (g) + O₂ (g) →  2CO₂ (g)

We must work with density to solve this problem

Density = Mass / volume

Let's determine the moles of O₂

1.43 g/mL = mass / 32500 mL

Notice, that we had to convert the volume from L, to mL, because the units of density.

Mass of O₂ → 1.43 g/mL . 32500 mL = 46475 g

Let's convert the mass to moles (mass / molar mas)

46475 g / 32 g/mol = 1452.3 moles

So ratio is 1:2

1 mol of oxygen needs 2 moles of CO, to react

Then, 1452.3 moles of O₂ would need the double of CO to react

1452.3 moles . 2 = 2904.6 moles of CO

This moles are contained in (mol . molar mass) =

2904.6 mol . 28 g/mol =81328.8 g

Density of CO = Mass of CO/ Volume of CO

1.25 g/mL = 81328.8 g / Volume of CO

81328.8 g / 1.25 g/mL  = 65063 mL

If we convert to L

65063 mL = 65.0 L

To react 32.5 liters of oxygen gas with carbon monoxide, the balanced chemical reaction shows a ratio of 2:1 between CO and O₂, thus requiring 65 liters of carbon monoxide.

The volume of carbon monoxide required to react with 32.5 liters of oxygen gas can be determined by looking at the coefficients in the balanced chemical equation of the reaction, which is not provided in the question but assuming a typical reaction between carbon monoxide and oxygen to form carbon dioxide, the equation is:

2 CO(g) + O₂(g) → 2 CO₂(g)

This equation shows that 2 volumes of CO react with 1 volume of O₂. Therefore, to find the volume of CO needed for 32.5 liters of O₂, you multiply the volume of O₂ by 2, because the ratio is 2:1.

The required volume of CO = 32.5 liters of O₂ × 2 (because of the ratio 2:1) = 65 liters of CO.

Answer: The correct choice is:

E) Both serine and leucine would be on the exterior of the globular protein.

Explanation:

The solubility and positioning of amino acids in a globular protein in aqueous solution are influenced by their side chains. Amino acids with hydrophilic (water-loving) side chains tend to be on the exterior of the protein where they can interact with water, while those with hydrophobic (water-fearing) side chains tend to be in the interior, away from water. In this case: Serine has a hydrophilic side chain (CH₂OH). Leucine has a hydrophobic side chain (CH₂CH(CH₃)₂). Therefore, you would expect serine to be on the exterior of the globular protein (interacting with water) and leucine to be in the interior (shielded from water). The correct choice is: E) Both serine and leucine would be on the exterior of the globular protein.

Answer:

3.2L

Explanation:

PV=nRT

since pressure and temperature are held constant we have V=nR

R is a constant also,

Thus; [tex]\frac{v1}{n1}=\frac{v2}{n2}[/tex]

v1=1.5L  , n1=3mol, n2=1.4mol

[tex]\frac{1.5}{3}=\frac{v2}{1.4}[/tex]

v2=[tex]\frac{1.5}{3}*1.4[/tex]

v2=3.2L

The sample size is 233.19 mg and the purity of the sample is 48.97%

Why?

The chemical reaction between Na₂CO₃ and HCl is

Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂

The sample size that will react with 40 mL of 0.1100 M HCl is found by applying the following conversion factor to go from L of solution of HCl to mg of Na₂CO₃:

[tex]0.04 Lsolution*\frac{0.1100molesHCl}{1L solution}*\frac{1 mole Na_2CO_3}{2 moles HCl}*\frac{105.99 gNa_2CO_3}{1 mole Na_2CO_3}*\frac{1000mg}{1 g}\\ \\=233.19mgNa_2CO_3[/tex]

Now, in order to find the percentage purity we have to apply another conversion factor to go from mL of solution of HCl to g of Na2CO3, and dividing everything over the mass of the soda ash sample, followed by multiplying the result times 100 to find the percentage:

[tex]0.04215 Lsolution*\frac{0.1100molesHCl}{1L solution}*\frac{1 mole Na_2CO_3}{2 moles HCl}*\frac{105.99 gNa_2CO_3}{1 mole Na_2CO_3}\\ \\=0.2457mgNa_2CO_3*\frac{100\%}{0.5017 g} = 48.97 \%\\[/tex]

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These chemistry problems involve calculating the moles of reactants in a stoichiometry equation to establish necessary sample size and the purity of a sample. By understanding these concepts, you can calculate the sample's purity and size.

The subject of this question is a stoichiometry problem, relating the amounts of reactants and products in a chemical reaction, and how to calculate a sample's purity. Stoichiometrically, each mole of sodium carbonate, Na2CO3, reacts with two moles of hydrochloric acid, HCl. Given the molarity of HCl (0.1100 M), you can calculate the number of moles by multiplying the molarity by the volume used in liters.

For the first question, it's given that the sample contains 40.00% Na2CO3. Therefore, the number of moles of HCl needed would be twice the number of moles of Na2CO3 (given that the reaction is 1:2). From there, you can calculate the required sample mass in milligrams.

For the second question, if it took 42.15 mL of 0.1100 M HCl to titrate a 0.5017 g sample, again calculate the moles of HCl used, and hence moles of Na2CO3. The mass of Na2CO3 is determined from its molar mass, and then the purity can be calculated as the mass of Na2CO3 divided by the total mass of the sample multiplied by 100%.

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Answer:

The answer to your question is 60 ml of solution 5% and 40 ml of solution 10 %

Explanation:

Data

acetic acid = 5% = concentration 1

acetic acid 2 = 10% = concentration 2

final solution = 7 % =

final volume = 100 ml

Process

1.- Write an equation of the process

x = volume of solution 5%

100 - x = volume of solution 10%

Final concentration x final volume = concentration 1 x volume 1 + concentration 2 x volume 2

      0.07(100) = 0.05x + 0.10(100 - x)

2.- Solve for x

                  7 = 0.05x + 10 - 0.1x

                 7 - 10 = 0.05 - 0.1 x

                   - 3 = -0.05 x

                     x = -3/-0.05

                     x = 60 ml of solution 5%

3.- Calculate the volume of solution 10%

     Volume of 10% = 100 - 60

     Volume of 10% = 40 ml        

Answer: option 3. No, because Celsius is not an absolute temperature scale.

Explanation:

Answer:

3. No, because Celsius is not an absolute temperature scale.

Explanation:

Note that  20∘C=293K  and  5∘C=278K . So the absolute temperature has not decreased by very much at all, certainly not by a factor of four. Therefore, the change in size of the plastic bottle would not be very noticeable.

Answer:

                    Major Product = 4-chloro-4-methylcyclohex-1-ene

Explanation:

                     Alkene are the class of organic compounds which contain one or more double bonds between two carbon atoms. Alkenes are considered most reactive among the unsaturated hydrocarbons and they undergo addition reactions due to high electron density around the double bonds.

                      In given question it is written that we are provided with one equivalent of HCl while, our compound contains two double bonds (diene) so in selected starting material the HCl will be added across (hydrohalogenation reaction) the substituted double bond because it will give a more stable carbocation (tertiary carbocation) during the reaction course. Hence, as shown in reaction scheme 4-chloro-4-methylcyclohex-1-ene will be the major product.

Answer:

5.19 m³  

Explanation:

Data Given:

initial Pressure P1 = atmospheric pressure

Reported atmospheric pressure =  14.696 psi

Final pressures P2 =  68 psi

initial Temperature T1 =  26 °C

final Temperature T2 =  48 °C

initial Volume V1= 13 m³

final Volume V2 = ?

Solution:

Formula will be used

                    P1 V1 / T1 = P2 V2 / T2

To calculate volume rearrange the above formula

                   V2 = (P1 V1) T2 / T1 P2 . . . . . . . .(1)

put values in equation 1

                  V2 = (14.696 psi x 13 m³) 48 °C / 26 °C x 68 psi

                  V2 = (191.05 psi m³) 48 °C / 1768 °C psi

                  V2 = (9170.3  psi m³ °C / 1768 °C psi

                  V2 = 5.19 m³

So, final volume is 5.19 m³                

Answer:

The answer to your question is pH = 9.08

Explanation:

Data

pH = ?

Concentration = 1.2 x 10⁻⁵ M

Process

1.- Calculate the pOH of the solution

Formula

   pOH = -log[OH⁻]

   pOH = -log[1.2 x 10⁻⁵]

   pOH = 4.92

2.- Calculate the pH

Formula

    pH = 14 - pOH

Substitution

    pH = 14 - 4.92

Result

    pH = 9.08    

Answer:

We need 28.5 mL of Calcium solution

Explanation:

Step 1: Data given

Density = 1.55 g/mL

Mass of calcium fluoride (CaF2) = 85.8 grams

Molar mass of CaF2 = 78.07 g/mol

Step 2: The balanced equation

Ca + 2HF → CaF2 + H2

Step 3: Calculate moles CaF2

Moles CaF2 = mass CaF2 / molar mass CaF2

Moles CaF2 = 85.8 grams / 78.07 g/mol

Moles = 1.10 moles

Step 4: Calculate moles of Ca

For 1 mol mol CaF2 we need 1 mol Ca^2+

For 1.10 moles CaF2, we need 1.10 moles Ca^2+

Step 5: Calculate mass of Ca^2+

Mass Ca^2+ = moles Ca^2+ / molar mass Ca^2+

Mass Ca^2+ = 1.10 moles * 40.08 g/mol

Mass Ca^2+ = 44.1 grams

Step 6: Calculate volume of Ca^2+

Volume Calcium = mass calcium / density

Volume calcium = 44.1 grams / 1.55 g/mL

Volume calcium = 28.45 mL ≈ 28.5 mL

We need 28.5 mL of Calcium solution

Answer:

The answer to your question is letter E. 288.4 g/mol

Explanation:

Data

Number of carbons = 19

mass percent of carbon = 79.12

molar mass = ?

Process

1.- Calculate the molar mass of 19 atoms of carbon

Atomic mass of carbon = 12 g

Atomic mass of 19 atoms of carbon = 228 g                            

2.- Use proportions to calculate the mass of testosterone

                        228 g ---------------  79.12 %

                           x      --------------      100 %                          

                          x = (228 x 100) / 79.12

Simplify

                          x = 22800 / 79.12

Molar mass of testosterone = 288.2 g          

The standard enthalpy of formation of CaC2(s) can be calculated using the provided enthalpy of the reaction and the standard enthalpies of formation for the other substances participating in the reaction, which can be found in Appendix C.

In order to calculate the enthalpy of formation (ΔH∘f) for CaC2(s) from the given enthalpy of reaction data, we will use the thermochemical equation and the data from the appendix. The given reaction, CaC2(s)+2H2O(l)→Ca(OH)2(s)+C2H2(g), has an enthalpy of -127.2kJ.

Using this we can rearrange the equation to find the enthalpy of formation of CaC2(s) i.e. ΔH∘f (CaC2(s)) = ΔH∘reaction + ΔH∘f (Ca(OH)2) + ΔH∘f (C2H2) - [ΔH∘f (CaC2) + 2×ΔH∘f (H2O)].

To find ΔH∘f for CaC2(s), we need the values of standard enthalpy of formation of the other substances participating in the reaction, which can be found in Appendix C.

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Answer:

A mole is equal to 6.022 × [tex]10^{23}[/tex] atoms/molecules.

Explanation:

A mole is a unit of measurement. Think of it as a unit of measurement just like a dozen of eggs is equal to 12 eggs, one mole is equal to 6.022 × [tex]10^{23}[/tex] atoms/molecules. This number, 6.022 × [tex]10^{23}[/tex], is known as Avogadro's number and you use it to convert from the number of moles to the number of atoms or molecules.

For example, if you want to convert 81 grams of water ([tex]H_{2}O[/tex]) to the number of atoms, you will need to use Avogadro's number. First, you have to find the molar mass of the water. To do this, you look at the periodic table and find the mass of hydrogen and oxygen because those are the elements that make up water. The subscript of the element tells you how many atoms of that particular element you have. So water has 2 hydrogen atoms and 1 oxygen atom. The molar mass tells you how many grams of a substance makes up 1 mole of that substance and it will vary by substance (no two different substances will have the exact same molar mass).

Molar Mass of Water: (2 × 1.008 g) + (1 × 15.999 g)= 18.015 grams

After we find the molar mass of the substance, we can use Avogadro's number to convert from grams to moles and then from moles to the number of atoms.

[tex]\frac{81 grams H_{2}O }{1} * \frac{1 mole H_{2}O }{18.015 grams H_{2}O } * \frac{6.022*10^{23} atoms}{1 mole H_{2}O } = 2.708*10^{24}[/tex] atoms of [tex]H_{2}O[/tex]

To convert grams to kilograms you need to know the conversion factor between them which is 1000 grams equals 1 kilogram. For example, if you are given 7,389 grams and you want to convert that to kilograms you do:

[tex]\frac{7389 grams}{1}[/tex] × [tex]\frac{1 kilogram}{1000 grams}[/tex] = 7.389 kilograms

I hope this helped clear things up a bit!

Answer:

The sketch and explanation is attached below.

Explanation:

Matter consists of atom, which is the smallest particle of an elements. Atoms consists of three parts; The protons which are positively charged, the neutrons which are neutral and the electrons which are negatively charged. both the proton and neutron make up the nucleus while the electron orbit outside of the nucleus.

Protons ; are positively charged which form the basis of the atoms. the symbol for protons is Z and the number of protons which make up an atom is also known as the atomic number which is a unique property of an element, no two elements must have the same atomic number.

Neutrons ; are neutral in an atom as such they do not have a charge and it is indicated by the letter N. the number of protons is the difference between the mass number and the atomic number of the proton number.

Electrons ; are negatively charged and they orbit outside of the nucleus of an atom. The mass of a proton is 1840 times greater than the mass of an electron.

Various scientist have given their own explanation of the model of an atom, people like Ernest rutherford, Neil bohr, John Dalton, JJ Thompson et al came up with different postulation of the atomic model. Neil bohr for example said about electrons they they do not only have energy, but they have a particular energy which are confined into energy levels that is the energy of the electrons were quantised. John dalton -the English scientist also came about his atomic theory ; each element has its own unique type of atom, atoms of each individual element have the same atomic weight, when atoms combine, they do so in fixed ratios. although most of dalton's theory have been modified.

An electron shell on the other hand comprises of the outer part of an atom i.e outside the nucleus. shells have sub-shells or sublevels. there are K-L-M shells. sodium (Na) for example has an atomic number of 11 and an electronic configuration of 2)8)1 - this implies that it has 3-shells -k-L-M and the last electron in its shells which is 1 is known as the valence electrons or the outermost electron. it is the number of electron at the outermost shell that takes part in the donating and accepting of electron.

Calcium(Ca) for example has an atomic number of 20, electronic configuration 2)8)8)2, K-L-M-N, it has four shells. the outermost electron (2) is the valence electron and it is the electron which determines the group of an element. this explains why sodium (Na) is a group 1 element and calcium (Ca) is a group 2 elements.

The valence electrons is the only electron that takes part in sharing during bonding. for example Sodium chloride(Nacl) - sodium has 1 electron at the outermost shell and chlorine has 7 electron in its outermost shell, hence its needs 1 more electron to attain the octet state , this 1 electron will be donated by Na to become a cation as such sodium becomes the reducing agent and chlorine is the oxidizing agent as it accept electron to become a anion. The essence of bonding or transfer or sharing of electrons is for atoms of element to either attain the octet or duplet state.

The atom model features a nucleus, electrons in shells, and valence electrons influencing bonding. Outer shell electron interactions drive covalent and ionic bonding, crucial in chemical reactivity.

The atom model is based on the understanding that atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in orbitals. The electrons are organized into electron shells, each with a specific energy level. The innermost shell is filled first before moving to the next, and the outermost shell determines the atom's chemical properties.

Electron shells are designated by principal quantum numbers (n), and each shell can accommodate a specific number of electrons. The first shell (n=1) can hold up to 2 electrons, the second (n=2) can hold up to 8, and so on. Electrons in the outermost shell are called valence electrons, and these play a crucial role in chemical bonding.

The number of electrons in the outermost shell influences an atom's reactivity. Atoms strive to achieve a full outer shell, following the octet rule. Some atoms achieve this by sharing electrons (covalent bonding), while others transfer electrons (ionic bonding). In covalent bonding, atoms share electrons to complete their outer shells, forming stable molecules. In ionic bonding, atoms transfer electrons, creating ions with full outer shells.

Understanding electron distribution in shells provides insight into an atom's behavior in chemical reactions, facilitating predictions about its bonding tendencies. This model, incorporating electron shells, enhances our comprehension of atomic structure and guides our understanding of chemical interactions.

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Answer:MnCO3+2H2O----->MnO2+ HCO3-+2e-+3H+

Explanation:The equation to be balanced is

MnCO3 ------> MnO2+HCO3-

The oxidation number of Mn changes from +2 in MnCO3 to +4 in MnO2

Therefore two electrons must be added to the right as shown below:

MnCO3 -------> MnO2+ HCO3-+ 2e-Now,there is one negative charge HCO3- and 1 negative charge on the two electrons making a total of -3 charges on the right. There is zero charge on the left.

To balance the equation,add3H+on the right,to cancel out the charges.

MnCO3 --------> MnO2+HCO3-+2e-+3H+

Adding H2O to balance Hydrogen and Oxygen atoms:

MnCO3+2H2O ------->MnO2+HCO3-+2e-+3H+

The half reaction for the oxidation of Manganese has been [tex]\rm MnCO_3\;+\;2\;H_2O\;\rightarrow\;MnO_2\;+\;HCO_3^-\;+\;2e^-\;+\;3\;H^+[/tex]

Oxidation has been defined as the loss of electrons by an element. The half reaction has been the oxidation reaction in the redox reaction.

In the reaction of Manganese carbonate to manganese dioxide, there has been change in the oxidation number of Mn from +2 to +4. The change in the oxidation state has been balanced with the addition of electrons.

The carbonate charge has been balanced in the reaction with the addition of hydrogen and water molecules.

The half reaction for the oxidation of Manganese has been [tex]\rm MnCO_3\;+\;2\;H_2O\;\rightarrow\;MnO_2\;+\;HCO_3^-\;+\;2e^-\;+\;3\;H^+[/tex]

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In the nickel nucleus, the atomic number indicates the number of protons, and the mass number represents the sum of protons and neutrons. When nickel forms a +2 ion, the number of protons remains the same, but electrons decrease and neutrons increase to maintain electrical neutrality.

In the nickel nucleus represented above, the atomic number 28 indicates that the nucleus contains 28 protons, and therefore, it must contain 30 neutrons to have a mass number of 58.

When the nickel atom forms a +2 ion, it loses 2 electrons and becomes 60-Ni+2.

However, the number of protons remains the same at 28 because the atomic number defines the element.

Therefore, 60-Ni+2 still has 28 protons, but the number of electrons decreases to 26.

To maintain electrical neutrality, the ion gains 2 more neutrons resulting in 32 neutrons.

Answer:

The answer to your question is mass = 455.6 grams

Explanation:

Data

Dimensions = 68.6 yd x 12 in x 0.00035 in

density = 2.70 g/cm³

mass = ?

Process

1.- Convert dimensions to cm

              1 yd ---------------- 91.44 cm

            68.6 yd ------------  x

              x = (68.6 x 91.44) / 1

              x = 6227 cm

             1 in ----------------- 2.54 cm

            12 in ---------------   x

              x = (12 x 2.54) / 1

              x = 30.48 cm

              1 in --------------  2.54

  0.00035 in -------------  x

              x = (0.00035 x 2.54) / 1

              x = 0.000889 cm

2.- Find the volume of the foil

      V = 6227 x 30.48 x 0.000889

      V = 168.73 cm³

3.- Find the mass of the foil

      mass = density x volume

      mass = 2.70 x 168.73

      mass = 455.6 g

Final answer:

To calculate the mass of the aluminum foil, first convert all dimensions to centimeters, then calculate the volume (length × width × height), and finally multiply the volume by the density of aluminum (2.70 g/cm³). Therefore, the mass of the aluminum foil is approximately 457.94 grams

Explanation:

To find the mass of the aluminum foil given its dimensions and the density of aluminum, we need to follow these steps:

Convert all measurements to the same unit system, specifically to centimeters (cm) because the density is given in g/cm3.

Calculate the volume of the aluminum foil using the formula for the volume of a rectangular prism: Volume = length × width × height.

Multiply the volume by the density of aluminum to get the mass of the foil.

Step-by-Step Calculation

First, convert dimensions: 68.6 yd = 6265.44 cm (1 yd = 91.44 cm), 12 in = 30.48 cm (1 in = 2.54 cm), and 0.00035 in = 0.000889 cm.

Calculate the volume: Volume = 6265.44 cm × 30.48 cm × 0.000889 cm = 169.609 cm3.

Calculate the mass: Mass = volume × density = 169.609 cm3 × 2.70 g/cm3 = 457.94 grams.

The mass of the aluminum foil is approximately 457.94 grams.

Answer:

Thus the  correct order would be  a, b,d  and then c

Explanation:

Rank of rock-forming minerals from most abundant to least abundant

1. Silicates

2. Carbonates

3. Oxides

4. Sulfates

Thus the  correct order would be  a, b,d  and then c

Answer:

6 mol of A₂B₃ are produced

Explanation:

This is the reaction:

4A  + 3B₂  →  2A₂B₃

4 moles of A react with 3 moles of B to produce 2 moles of A₂B₃.

Ratio is 4:2. Therefore:

4 moles of A will produce 2 moles of A₂B₃

12 moles of A, would produce (12 .2) / 4 = 6 moles

By applying the stoichiometric ratios from the balanced chemical equation 4A + 3B2 -> 2A₂B₃, it's determined that reacting 12 moles of A with excess B₂ will result in the production of 6 moles of A₂B₃.

To solve this, we look at the balanced chemical equation given: 4A + 3B₂ -> 2A₂B₃. This equation tells us that 4 moles of A react with 3 moles of B₂ to produce 2 moles of A₂B₃. Using this ratio, we can set up a proportion to find out how many moles of A₂B₃ will be produced when 12 moles of A are used. Since 4 moles of A yield 2 moles of A₂B₃, 12 moles of A will yield:

(12 moles A / 4 moles A) * 2 moles A₂B₃ = 3 * 2 moles A₂B₃ = 6 moles A₂B₃.

Therefore, reacting 12 moles of A with an excess of B₂ will produce 6 moles of A₂B₃.

Answer: B) an oxygen atom in a different molecule.

Explanation:

Hydrogen bonding (H-bonding) is an inter molecular force having partial ionic-covalent character.

H-bonding takes place between a hydrogen atom attached with an electronegative atom such as O, N and F and an electronegative atom such as O,N and F. They are strong forces.

Example: [tex]H_2O[/tex] has hydrogen bonding between hydrogen of one molecule with oxygen atom bonded to hydrogen of different molecule.

Thus the correct option is hydrogen bonding occurs between the hydrogen atom in one molecule and an oxygen atom in a different molecule.

In water, hydrogen bonding occurs between the hydrogen atom in one water molecule and the oxygen atom in a different water molecule. This is due to the large dipole moment caused by oxygen being more electronegative than hydrogen.

In a water molecule, hydrogen bonding occurs between the hydrogen atom of one molecule and an oxygen atom in a different molecule. Water molecules have a bent shape, with two hydrogen atoms and one oxygen atom. Because oxygen is more electronegative, the shared electrons between hydrogen and oxygen tend to stay closer to the oxygen atom, causing a dipole moment.

This dipole moment results in a partially positive charge on the hydrogen atoms and a partially negative charge on the oxygen atom. Hence, the hydrogen atoms from one water molecule are attracted to the oxygen atoms of another water molecule, forming hydrogen bonds.

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Answer:

Kinetic Energy is involved here

Explanation:

On a warm day, the temperature of H20(l) will be high and that will make the particles of water to possess more kinetic energy and particles tend to move faster. Due to the fast movement of the particles, some of the particles turns into gaseous form (vapour). This makes the volume (concentration) of the liquid water decrease while that of the vapour keeps increasing due to the temperature of the day, until the equilibrium point is reached. At the equilibrium point, the forward and the backward rates are equal and the concentration of liquid water and vapour is the same.

Answer:

Sodium-calcium exchanger on the sarcolemma

Explanation:

The sodium-calcium exchanger which is an antiporter membrane protein, removes calcium from cells. The energy of the electrochemical gradient of sodium is used by allowing it to flow down its gradient while moving across the plasma membrane

Answer:

D

Explanation:

the zero is trailing with a decimal so it counts. A is wrong because you can't round up, C is too many SF and E is wrong because a negative exponent would give you .001250

Answer: D

Explanation:

Not A: You don’t round up to 1251 because 3 is less than 5

Not B: That’s more than 4 sig figs

Not C: More than 4 sig figs

D: 1.250 has 4 sig figs and 1250 is the correct answer

Not E: negative exponent makes it into decimal which is way off

Answer:D. Powder react with vinegar

Explanation: All the other choice is physical change. Choice A is a change of color but it doesn’t change the properties. Choice B is an example of physical change which is simply for measurements therefore doesn’t affect the properties. Choice C is also physical change because solubility and dissolve are type of physical change leaving us with the last choice which is choice D. Since the powder reacts with the vinegar it changes the property of the powder.

The reaction between the white powder and vinegar is a chemical property where the chemical bonds are involved in the change to produce new products.

There are broadly two types of properties called physical properties and chemical properties. Physical properties involves the color, size, shape , phase, and phase transitions etc. Boiling point, melting point, solubility etc are physical properties.

Chemical properties include the changes in chemical bond between atoms such as breaking or formation or both for chemical bonds. The reaction between two compounds leads to breaking and making of chemical bonds and form new products.

Density, solubility, color etc are physical properties of the substance whereas its reactivity towards vinegar is a chemical property. Hence, option D is correct.

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Answer:

A. 0.433 moles of HNO₃

B. 6.07×10⁻⁵ moles of NaCl

C.  3.51×10⁻³ moles of sucrose

Explanation:

Part A.

Molarity . volume = moles

1.70 mol/L . 0.255L = 0.433 moles

Part B.

1.35 m of NaCl means, a molal concentration (m). Moles of solute in 1kg of solvent.

Let's convert 1 kg to mg for the rule of three

1 kg = 1×10⁶ mg

So in 1×10⁶ mg of solvent, we have 1.35 moles of solute (NaCl)

In 45 mg, we would have ( 45 . 1.35) / 1×10⁶ = 6.07×10⁻⁵ moles of NaCl

Part C. 1.50 % by mass means, 1.50 g of solute, in 100g of solution.

Let's make a rule of three:

In 100 g of solution we have 1.50 g of sucrose

In 80 g of solution, we would have (80 . 1.50) / 100 =1.2 g of sucrose.

Then, let's convert the mass in moles ( mass / molar mass)

1.2 g / 342 g/m = 3.51×10⁻³ moles

(A) 0.433 moles of HNO₃ in 255mL of 1.70M HNO3

(B) 6.07×10⁻⁵ moles of NaCl in 45.0mg of an aqueous solution that is 1.35m NaCl

(C) 3.51×10⁻³ moles of sucrose in an aqueous solution that is 1.50% sucrose (C12H22O11) by mass

(A) 255mL of 1.70M HNO3(aq)

Molarity × volume = moles

1.70 × 0.255L = 0.433 moles of HNO3

(B) 45.0mg of an aqueous solution that is 1.35m NaCl

1.35 m of NaCl means, a molal concentration (m). Moles of solute in 1kg of solvent.

In 45 mg, the number of moles is:

45 × 1.35 / 1×10⁶ = 6.07×10⁻⁵ moles of NaCl

(C) 80.0g of an aqueous solution that is 1.50% sucrose (C12H22O11) by mass

the solute is 1.50 % by mass, that is :

1.50 g of solute, in 100g of solution.

In 80 g of solution

80 × 1.50 / 100 =1.2 g of sucrose.

Now, convert the mass in moles

number of moles = given mass / molar mass

1.2 g / 342 g/m = 3.51×10⁻³ moles of sucrose

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Answer:

498.95 ml of formula per day

Explanation:

Baby body requirement of copper per day = 80.0. μg per Kg

Copper content of formula = 0.48 μg/mL.

Mass of baby = 6.60 lb

1 lb = 0.4536 Kg

6.6 lb = 2.9937 Kg

Therefore baby needs

80μg/Kg/day × 2.9937 Kg = 239.5μg/day of formula

But formula contains 0.48 μg/mL that means baby needs

(239.5 μg/day)÷0.48 μg/mL = 498.95 ml of formula per day

498.95 ml/day

Answer:

The electrons are exposed to thermal energy/heat causing the excitation of the electron that is the electron in the outer orbital get absorbed and bounce to higher energy level.

Under the spectroscope, omitted wavelengths are seen with bright colors. For instance, light with longer wavelength appears red and light with shorter wavelength appear purple.

So, therefore, different metals will produce different wavelengths of light that are giving off a characteristic color of light.

Comparing the position of the colored light helps in the identification of substances.

When a substance is vaporized in a flame, the activity of electrons can be observed. The light emitted by the substance can be viewed through a spectroscope, which can help identify the substance based on its characteristic spectral lines or patterns.

When a substance is vaporized in a flame, the activity of electrons can be observed. This is because the high temperature of the flame causes the electrons in the substance to become excited and move to higher energy levels. When these excited electrons return to their ground state, they release energy in the form of light.

The light emitted by the substance can be viewed through a spectroscope, which is an instrument used to separate light into its different wavelengths or colors. By analyzing the specific wavelengths of light emitted, scientists can identify the substance based on its characteristic spectral lines or patterns.

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Answer : The atomic mass of E is, 30.4 g/mol

Explanation :

If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given.

Mass of E = 27.52 g

Mass of S = 72.48 g

First we have to calculate the moles of sulfur.

Moles of S = [tex]\frac{\text{ given mass of S}}{\text{ molar mass of S}}= \frac{72.48g}{32g/mole}=2.265moles[/tex]

Now we have to calculate the moles of E by comparing the stoichiometry of the compound.

The given compound formula is, [tex]E_4S_{10}[/tex]

As, 10 moles of sulfur combine with 4 moles of E

So, 2.265 moles of sulfur combine with [tex]\frac{2.265}{10}\times 4=0.906[/tex] moles of E

Thus, the moles of E is, 0.906 moles.

Now we have to calculate the atomic mass of E.

Atomic mass of E = [tex]\frac{\text{ given mass of E}}{\text{ moles of E}}= \frac{27.52g}{0.906mole}=30.4g/mol[/tex]

Thus, the atomic mass of E is, 30.4 g/mol

A precipitation reaction is indicated by the formation of a solid that settles out when two aqueous solutions are mixed. The correct answer is Option b.

When two different aqueous solutions are mixed in a test tube, a precipitation reaction can be indicated by the formation of a solid that settles out. This occurs when two soluble compounds react to form an insoluble compound, which appears as a solid precipitate. Examples of precipitation reactions include mixing solutions of silver nitrate and sodium chloride to form a solid precipitate of silver chloride.

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Final answer:

The observation that most directly indicates a precipitation reaction when two aqueous solutions are mixed is b. A solid settles out, as this signifies the formation of a precipitate, which is a solid product of the reaction.

Explanation:

The question asks which observation is most indicative of a precipitation reaction when mixing two different aqueous solutions. Among the options given, the correct answer is b. A solid settles out. This is because a precipitation reaction involves the formation of a solid product, known as a precipitate, that separates from the clear solution. This precipitate can then typically be observed as sediment at the bottom of the test tube, or as a solid pellet if centrifugation is used. Options a, c, and d refer to other potential indicators of chemical reactions, such as gas formation, color change, and exothermic reactions, respectively, and while they may occur alongside precipitation, they are not as directly indicative of it.

Answer:

The given atom is of Ca.

Explanation:

Given data:

Speed of atom = 1% of speed of light

De-broglie wavelength = 3.31×10⁻³ pm (3.31×10⁻³ / 10¹² = 3.31×10⁻¹⁵ m)

What is element = ?

Solution:

Formula:

m = h/λv

m = mass of particle

h  = planks constant

v = speed of particle

λ = wavelength

Now we will put the values in formula.

m = h/λv

m = 6.63×10⁻³⁴kg. m².s⁻¹/3.31×10⁻¹⁵ m ×( 1/100)×3×10⁸ m/s

m = 6.63×10⁻³⁴kg. m².s⁻¹/ 0.099×10⁻⁷m²/s

m = 66.97×10⁻²⁷ Kg/atom

or

6.69×10⁻²⁶ Kg/atom

Now here we will use the Avogadro number.

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

Now in given problem,

6.69×10⁻²⁶ Kg/atom × 6.022 × 10²³ atoms/ mol × 1000 g/ 1kg

40.3×10⁻³×10³g/mol

40.3  g/mol

So the given atom is of Ca.

The movement of sounds, in the same manner, is called wavelength.

The correct element is Ca.

The data in the question is as follows:-

The formula we will used is [tex]m = \frac{h}{λv}[/tex]

The data is given is as follows:-

Now we will put the values in the formula and solve the equation.

[tex]m = \frac{6.63*10^{-34}}{3.31*10^{-15} ( \frac{1}{100})*3*10^8}[/tex]

After solving the value of m is[tex]66.97*10^{-27}[/tex]

Now in the given problem, the solution is as follows:-

[tex]6.69*10^{-26}* 6.022 * 10^{23} * 1000[/tex]

After solving the equation the answer is 40.3

Hence, the 40.3 is the mass of calcium.

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