Which of the following describes an element that is reduced in a reaction? It acts in the reactant that is the reducing agent. It has a decrease in its oxidation number. Cd yields Cd2+ + 2e− Zn + Cu2+ yields Zn2+ + Cu

Final answer:

An element with a 2+ charge has two more protons than electrons, as protons have a positive charge of +1 each.

Explanation:

If an element has a charge of 2+, it means that the element has two more protons than electrons. Since protons carry a positive charge of +1, a 2+ charge indicates that the number of protons exceeds the number of electrons by two. For example, calcium has an atomic number of 20, meaning it has 20 protons. As a Ca2+ ion, it would have 18 electrons, as it would have lost two electrons to acquire the 2+ charge.

To make a 2.5 w/v solution of NaOH, you will need 2.5 grams of NaOH for every 100 mL of solution. Solving for 750 mL, you would need 18.75 grams of NaOH.

The question refers to a w/v (weight/volume) concentration. This concentration is defined as the amount of solute (in this case, NaOH) in grams that is present in 100 mL of solution.To make a 2.5 w/v solution of NaOH, you will need 2.5 grams of NaOH for every 100 mL of solution.

First, let's set up a ratio to find out how many grams of NaOH are needed for 750 mL of solution:

(2.5 g NaOH / 100 mL solution) = (x g NaOH / 750 mL solution)

Cross-multiply to solve for x:

x = (2.5 g NaOH * 750 mL solution) / 100 mL solution = 18.75 g NaOH

So, you would need 18.75 grams of NaOH to make 750 mL of a 2.5 w/v NaOH solution.

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Answer:

Explanation:

3.86 L CO  x  1 mol O2  x  1mole O2   x  22.4 L O2  =  1.93 L O2

                   22.4 L CO     2 mole CO      1 mole O2

The volume of oxygen, O₂ in litre (L) required to burn 3.86 L of carbon monoxide , CO is 1.93 L

2CO + O₂ —> 2CO₂

From the balanced equation above,

2 L of CO requires 1 L of O₂

From the balanced equation above,

2 L of CO requires 1 L of O₂

Therefore,

3.86 L of CO will require = 3.86 / 2 = 1.93 L of O₂

Thus, 1.93 L of O₂ is needed for the reaction

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4 dozen eggs= 48 eggs

48 eggs/ 3 eggs

16 three egg omelets can be made

CaCO₃ will precipitate when aqueous solutions of sodium carbonate  and calcium chloride are mixed

There are two types of chemical reactions that may occur.

namely single-replacement reactions and double-replacement reactions.

1. A single replacement reaction is a chemical reaction in which one element replaces the other elements of a compound to produce new elements and compounds

Not all of these reactions can occur. We can use the activity series, which is a list of elements that can replace other elements below / to the right of them in a single replacement reaction.

This series is better known as the Volta series, where the metal element with a more negative electrode potential is on the left, while the element with a more positive electrode potential on the right.

The more left the position of a metal in the series, the more reactive metal (easy to release electrons, the stronger the reductor)

Generally, the Volta series used is

Li K Ba Sr Ca Na Mg Al Mn Zn Cr Fe Cd Co Ni Sn Pb H Sb Bi Cu Hg Ag Pt Au

Example:

2Al (s) + 3Zn (NO₃) ₂ (aq) → 2Al (NO₃) ₃ (aq) + 3Zn (s)

The existing aluminum element can replace the zinc element, which is on the right side so the reaction will occur.

2. Double-Replacement reactions. Happens if there is an ion exchange between two ion compounds in the reactant to form two new ion compounds in the product

To predict whether this reaction can occur or not is one of them, the precipitation reaction. A precipitation reaction occurs if two ionic compounds which are dissolved reacted to produce one of the products of the ion compound does not dissolve. Formation of these precipitating compounds that cause reactions can occur

Solubility Rules:

All compounds of Li +, Na +, K +, Rb +, Cs +, and NH4 +

All compounds of NO₃⁻ and C₂H₃O₂⁻

Compounds of Cl−, Br−, I− except Ag⁺, Hg₂²⁺, Pb²⁺

Compounds of SO₄²⁻ except Hg₂²⁺, Pb²⁺, Sr²⁺, Ba²⁺

Compounds of CO₃²⁻ and PO₄³⁻ except for Compounds of Li +, Na +, K +, Rb +, Cs +, and NH₄ +

Compounds of OH− except Compounds of Li +, Na +, K +, Rb +, Cs +, NH₄⁺, Sr²⁺, and Ba²⁺

In reaction:

sodium carbonate (Na₂CO₃) and calcium chloride (CaCl₂)

Na₂CO₃ (aq) + CaCl₂ (aq) ⇒ 2NaCl (aq) + CaCO₃ (s)

The precipitated compound is CaCO₃ so that Double-Replacement reactions between Na₂CO₃ and CaCl₂ can occur

A double-replacement equation

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the reducing agent

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substance loses electrons in a chemical reaction

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Answer: The product formed from the reaction of these two is sulfurous acid.

Explanation:

When sulfur dioxide reacts with water molecule, it leads to the formation of an acid known as sulfurous acid.

The chemical reaction for the combination of sulfur dioxide and water follows the equation:

[tex]SO_2(g)+H_2O(l)\rightarrow H_2SO_3(aq.)[/tex]

By Stoichiometry of the reaction:

1 mole of sulfur dioxide reacts with 1 mole of water molecule to produce 1 mole of sulfurous acid.

Hence, the product formed from the reaction of these two is sulfurous acid.

Electrons are negatively charged

Neutrons are neutrally charged

Protons are positively charged

Answer: Option (C) is the correct answer.

Explanation:

According to ideal gas law, product of pressure and volume equals n times R times T.

Mathematically,       PV = nRT

where         P = pressure

                  V = volume

                  n = number of moles

                  R = gas constant

                  T = temperature

Since it is known that value R = 0.082 L [tex]atm mol^{-1} K^{-1}[/tex] and the other values are given as P = 15.0 atm, V = 100 mL = 0.1 L, and n = 0.5 moles.

Therefore, calculate value of temperature as follows.

                           PV = nRT

                [tex]15 atm \times 0.1 L[/tex] = [tex]0.5 moles \times 0.082 L atm mol^{-1} K^{-1} \times T[/tex]

               T = 36.58 K

Thus, we can conclude that temperature is 36.5 K.

The definition of molarity is:

Molarity = moles of solute / total volume of solution in Liters

In this case, our solute is Sulfuric Acid. To solve this problem, let us assume a basis for calculation.

Let us say that,

Total mass of solution = 100 g

Therefore mass of H2SO4 = 20 g

The molar mass of H2SO4 = 98.079 g / mol

Calculating for number of moles of H2SO4:

number of moles = 20 g / (98.079 g / mol)

number of moles = 0.204 mol

Calculating for the volume of solution using the density:

total volume of solution = 100 g / (1.105 g / mL)

total volume of solution = 90.50 mL = 0.0905 L

Therefore the molarity is:

Molarity = 0.204 mol / 0.0905 L

Molarity = 2.2542 mol / L

Molarity = 2.25 M

Answer:

The answer would be A). H2O and OH- are added as needed to the half-reaction equations to make the number of oxygen and hydrogen atoms balance.

Answer: The balanced chemical equation is given below.

Explanation:

Every balanced chemical equation follows law of conservation of mass.

This law states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form. This law also states that total number of individual atoms on the reactant side must be equal to the total number of individual atoms on the product side.

For the given reaction, the balance chemical equation follows:

[tex]6NaBr+Ca_3(PO_4)_2\rightarrow 3CaBr_2+2Na_3PO_4[/tex]

By stoichiometry of the reaction:

6 moles of sodium bromide reacts with 1 mole of calcium phosphate to produce 3 moles of calcium bromide and 2 moles of sodium phosphate.

The maximum mass of carbon dioxide that could be produced by the reaction will be 53 g

From the equation of the reaction:

2C2H6 +7O2 ---> 4CO2 + 6H2O

Mole of 18 g ethane = 18/30

                                 = 0.6 moles

Mole of 85.4 g O2 = 85.4/32

                              = 2.67 moles

mole ratio of ethane and oxygen gas = 2:7

Thus, O2 gas seems to be in excess and C2H6 is the limiting reagent.

Mole ratio of C2H6 and CO2 = 1:2

Equivalent mole of CO2 = 0.6 x 2

                                          = 1.2 moles

Mass of 1.2 moles CO2 = 1.2 x 44.01

                                      = 52.81

                                        = 53 g to 2 significant digits

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The maximum mass of carbon dioxide that could be produced by the chemical reaction is 52.8 g.

To find the maximum mass of carbon dioxide produced in the reaction, we need to determine the limiting reagent, which is the reactant that is completely consumed first. We can do this by comparing the moles of ethane and oxygen and calculating how many moles of carbon dioxide can be produced from each.

First, calculate the number of moles of ethane:

Mass of ethane = 18 g

Molar mass of ethane = 2(12.01 g/mol) + 6(1.01 g/mol) = 30.07 g/mol

Moles of ethane = mass of ethane / molar mass = 18 g / 30.07 g/mol = 0.599 mol

Next, calculate the number of moles of oxygen:

Mass of oxygen = 85.4 g

Molar mass of oxygen = 2(16.00 g/mol) = 32.00 g/mol

Moles of oxygen = mass of oxygen / molar mass = 85.4 g / 32.00 g/mol = 2.67 mol

Now we can compare the mole ratios of ethane and oxygen in the balanced chemical equation:

2 moles of ethane react with 7 moles of oxygen to produce 4 moles of carbon dioxide.

Using the mole ratios, we can calculate the number of moles of carbon dioxide produced:

Moles of carbon dioxide = (0.599 mol ethane) x (4 mol CO2 / 2 mol ethane) = 1.20 mol CO2

Finally, we can calculate the maximum mass of carbon dioxide:

Mass of carbon dioxide = moles of carbon dioxide x molar mass of carbon dioxide = 1.20 mol x 44.01 g/mol = 52.8 g

Therefore, the maximum mass of carbon dioxide that could be produced is 52.8 g, rounded to 2 significant digits.

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Answer: b. Reaction A is not enzyme-catalyzed, while reaction B is enzyme-catalyzed

Explanation:

Activation energy is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.  It is the difference between the energy of activated complex and energy of reactants.

A catalyst is a substance which increases the rate of a reaction by taking the reaction through a different path which involves lower activation energy and thus more molecules can cross the energy barrier and convert to products.

The catalyst itself does not take part in the chemical reaction and is regenerated as such at the end.

Change in color is an indicator which most likely suggests that a chemical change is taking place. Most of the chemical indicators show a change in color with a proceed in the process. Thus, the correct option is B.

A chemical change occurs when a new substance (product) is formed or the original substance changes its identity and composition in presence of certain conditions due to a chemical reaction.

Chemical change is the opposite of a physical change which results due to modifications only in the physical properties such as the state or shape of matter. Moreover, a chemical reaction can be identified as it often leads to a change in color, odor, the emission of gases or temperature change. This implies that a chemical change is a change of color as this occurs if the composition of a substance change.

Therefore, the correct option is B.

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The mass percent ( m ÷ m ) of a solution prepared by dissolving 55.84 g of NaCl in 152.7 g of H₂O is 26.78 %

Mass is a physical body's total amount of matter. Inertia, or the body's resistance to acceleration when a net force is applied, is also measured by this term.

The intensity of an object's gravitational pull to other bodies is also influenced by its mass. The kilogram is the primary mass unit in the SI.

The amount of matter that makes up every item or body is the greatest way to understand mass. Everything that we can see has mass. Examples of objects with mass include a table, a chair, your bed, a football, a glass, and even air.

m ( NaCl)   = 55.84 g  and m ( H2O ) = 157.2 g.

m (  solution) = m ( NaCl ) +  m ( H₂O )

w ( NaCl ) = 100 m ( NaCl ) ÷ m (  solution ) = 100 m   ( NaCl )  / ( m ( NaCl ) + m ( H₂O )

w ( NaCl ) = 100 × 55.84/  ( 55.84+152.7 ) = 26.78%

Thus, the mass percent ( m ÷ m ) of a solution prepared by dissolving 55.84 g of NaCl in 152.7 g of H₂O is 26.78 %

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Answer:

The concentration of hydronium ions in solution is [tex]2.75\times 10^{-3} M[/tex].

Explanation:

The pH of the solution is defined as negative logarithm of hydronium ions concentration in a solution. Mathematically written as:

[tex]pH=-\log[H_3O^+][/tex]

Given, the pH of the solution = 2.56

[tex]2.56=-\log[H_3O^+][/tex]

[tex][H_3O^+]=0.002754 M=2.75\times 10^{-3} M[/tex]

The concentration of hydronium ions in solution is [tex]2.75\times 10^{-3} M[/tex].

An oxygen atom can accommodate 2 more electrons in its valence shell by forming two single bonds or one double bond to satisfy the octet rule.

The question concerning the number of additional electrons that can fit within the valence shell of an oxygen atom relates to its electron configuration and bonding capabilities. An oxygen atom typically has 6 electrons in its valence shell. To satisfy the octet rule, an oxygen atom requires 2 more electrons to complete its outermost shell. Oxygen achieves this by forming two single bonds with other atoms or one double bond, sharing electrons to fill the valence shell and reach a stable configuration with 8 electrons.

Oxygen, being in group 6 of the periodic table, has a valence electron count of 6 (electronic configuration: 2s²2p⁴). This means that the atom has two electrons that can pair up with electrons from other atoms, giving oxygen a valency of 2. By forming bonds, oxygen can have a filled valence shell with a total of 8 electrons, achieving the stable octet configuration.

In PCl₅, P the first element is phosphorus. Cl is the second element chlorine and chlorines ide name is chloride. PCl₅ is called as phosphorus pentachloride.

A crystalline substance that is greenish-yellow in color and has an offensive smell is phosphorus pentachloride. Water breaks it down into heat, hydrochloric acid, and phosphoric acid. This heat may be enough to start nearby combustible stuff on fire.

It is quite similar to identifying basic ionic compounds to name binary (two-element) covalent compounds. The first component of the formula is only the element's name mentioned. By taking the element name's stem and adding the suffix -ide, the second element is given a name.

Prefixes are used to define the number of atoms of each element in a compound's molecule because molecules of molecular compounds might generate compounds with varied ratios of their constituent elements. Ones that come to mind include SF6, sulfur hexafluoride,

Thus,  PCl₅ is called as phosphorus pentachloride.

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Final answer:

Using the enthalpy of vaporization for water, the energy from a candy bar could vaporize approximately 0.421 liters of water at 100°C.

Explanation:

To determine how much water could be vaporized from the energy obtained from a candy bar, we need to use the enthalpy of vaporization of water at 100°C, which is given as 40.7 kJ/mol. This value tells us the amount of energy needed to convert one mole of water from liquid to gas at these conditions.

First, we convert the energy in kJ from the candy bar to moles of water using the enthalpy of vaporization:

955 kJ × (1 mol / 40.7 kJ) = 23.46 moles of water

Next, we'll convert the moles of water to grams since we know the molar mass of water is approximately 18 g/mol:

23.46 moles × 18 g/mol = 421.28 grams of water

Finally, given that the density of water is 1.00 g/mL and that 1 liter equals 1000 mL, we convert grams to liters:

421.28 g × (1 mL / 1 g) × (1 L / 1000 mL) = 0.421 L of water

Therefore, the energy from the candy bar could vaporize approximately 0.421 liters of water.