As a technician in a large pharmaceutical research firm, you need to produce 300. mL of 1.00 M a phosphate buffer solution of pH = 7.36. The pKa of H2PO4− is 7.21. You have 2.00 L of 1.00 M KH2PO4 solution and 1.50 L of 1.00 M K2HPO4 solution, as well as a carboy of pure distilled H2O. How much 1.00 M KH2PO4 will you need to make this solution?

Final answer:

Copper can lend one or two electrons per atom in chemical reactions, commonly two for the reduction of Cu²⁺ ions, and has free conduction electrons that make it an excellent electrical conductor.

Explanation:

Copper can lend different numbers of electrons depending on the chemical process involved. For instance, in a redox reaction where copper ions are being reduced, two electrons are typically required to reduce a single Cu²⁺ ion to metallic copper (Cu). Since the atomic structure of copper allows for an outermost electron to be loosely bound, copper can conduct electricity well due to the movement of these conduction electrons.

In a typical copper wire or sheet, there is one free electron per atom that can be transferred. However, the number of electrons a copper atom can lend is not unlimited; it is restricted by the reaction conditions and the valence of the copper involved in the reaction.

Answer:

Oxygen - non polar

Carbon Dioxide - non polar

Explanation:

Oxygen is non polar because it is a covalent bond with equal electronegativity.

Carbon dioxide is also non polar because it has 2 Oxygen atoms which are as I stated above they are equally electronegative.

Oxygen is a nonpolar molecule as it consists of two identical atoms sharing electrons equally. Carbon dioxide is also nonpolar because, despite having polar covalent bonds, its linear shape causes the partial charges to cancel each other out.

The question asks whether each given molecule, oxygen, and carbon dioxide is polar or nonpolar and to explain the reasoning behind the classification. The polarity of a molecule is determined by both the electronegativity of the atoms and the overall molecular geometry. Oxygen (O2) is a homonuclear diatomic molecule, meaning it consists of two identical atoms that share the electrons equally, and as a result, it is a nonpolar molecule.

Carbon dioxide (CO2), on the other hand, is a linear molecule with two polar covalent bonds between carbon and oxygen. However, due to the symmetry of its linear shape, the partial charges on the molecule cancel each other out, making it a nonpolar molecule.

C. pressure is directly proportional to the absolute temperature

Explanation:

Answer:

C. Pressure is directly proportional to the absolute temperature.

Explanation:

I took the test :)

Answer:

They change the rate of reaction.

Explanation:

Temperature increases the rate of reaction as particles move faster.

(Temperature is the average kinetic energy of particles)

Reducing the particle size increases the surface area to volume ratio, which increases the rate of reaction.

Answer:

Format: What are the effects of X and Y on Z?

Independent variable 1: temperature

Independent variable 2: particle size

Dependent variable: reaction rate

Explanation:

i just answered it on e2020

Answer:

                      %Copper  =  25.42 %

Explanation:

                    For solving this problem one first write down the half reactions as;

Reduction of Cu²⁺ to Cu⁺¹ by I⁻:

                                2 Cu²⁺  +  4 I⁻   →   2 CuI  +  I₂

Secondly, the titration reaction between Na₂S₂O₃ with I₂ as;

                             2 S₂O₃²⁻  +  I₂   →   S₄O₆²⁻  +  2 I⁻

Now, Calculate Moles of S₂O₃²⁻ as;

                             Moles  =  Molarity × Volume

Putting values,

                             Moles  =  0.1 mol/L × 0.02 L

                             Moles  =  0.002 moles of S₂O₃²⁻

From first two equations we can conclude that,

2 moles of S₂O₃²⁻ liberated I₂ produced by  =  2 moles of Cu²⁺

So,

0.002 moles of S₂O₃²⁻ will liberate I₂ produced by  = X moles of Cu₂⁺

Solving for X,

                       X =  0.002 mol × 2 mol / 2 mol

                       X  =  0.002 mol of Cu²⁺

So, we require 0.002 moles of Cu²⁺ to produce I₂ enough for titrating with 0.1 M (20.00 mL) sodium thiosulphate solution.

Now, Calculate mass of Copper as,

                       Mass  =  Moles  ×  A.Mass

                       Mass  =  0.002 mol × 63.55 g/mol

                       Mass  =  0.1271 g of Copper

Lastly, calculate % copper as,

                       %Copper  =  0.1271 g / 0.500 g × 100

                       %Copper  =  25.42 %

Final answer:

To calculate the percent copper in a sample using iodometric titration, the amount of sodium thiosulphate used in the titration reveals the moles of copper present. The mass of copper is then calculated, allowing us to find that the sample is 25.42% copper.

Explanation:

To determine the percent copper in the sample using iodometric titration, we first need to understand the chemistry involved. The reaction between Copper (II) and iodide produces iodine, which is then titrated with sodium thiosulphate. The formula for calculating the percent copper is based on the stoichiometry of these reactions.

Given that 20.00 [tex]cm^3[/tex] of 0.1 M sodium thiosulphate is required, we can calculate the moles of sodium thiosulphate reacted: Moles of sodium thiosulphate = 20.00 [tex]cm^3[/tex] × 0.1 mol/L = 0.0020 mol.

Sodium thiosulphate reacts with iodine in a 1:1 molar ratio, meaning 0.0020 mol of iodine was produced. The stoichiometry between copper (II) and iodine is also 1:1, so 0.0020 mol of Copper (II) was initially present. The molar mass of Copper (II) is 63.546 g/mol, hence the mass of copper in the sample is 0.0020 mol × 63.546 g/mol = 0.1271 g.

To find the percent copper, we then use the formula: Percent Copper = (Mass of Copper in the Sample / Total Mass of the Sample) × 100 = (0.1271 g / 0.500 g) × 100 = 25.42%.

The correct image is option A

What happens when we add NaCl to water?

The process of dissolving table salt (NaCl) in water is known as dissolution. The salt separates into sodium (Na⁺) and chloride (Cl⁻) ions, which are its component ions. These ions, which are charged positively or negatively, interact with the molecules of water to surround and disseminate themselves.

A homogenous mixture known as saltwater is created as a result. The ionic connections holding the salt crystal lattice together are broken during the physical process of NaCl dissolving in water, distributing the ions uniformly throughout the solution.

The diagram  that best ilustrates the ion-molecule attractions that occur when the ions of NaCl(s) are added to water is option B)

When sodium chloride (NaCl) is added to water, it dissolves and dissociates into Na+ and Cl- ions. These ions are then surrounded by water molecules due to ion-dipole attractions. Water molecules are polar, with a partially negative oxygen atom and partially positive hydrogen atoms.

The positive sodium ions are attracted to the negative oxygen atoms in the water molecules, and the negative chloride ions are attracted to the positive hydrogen atoms. This results in the formation of a hydrated lattice, where the ions are surrounded by water molecules.

Answer:

9.4×10⁴J

Explanation:

The specific heat capacity (SHC) of water, which is the amount of energy (J) that it takes to warm 1mL (1mL = 1g) of water by 1°C is 4.184 J/g×°C.

Q = mcΔT relates energy to mass, SHC, and change in temperature.

The mass of water is 300g, and will not change because no water will evaporate until it reaches 100°C.

The change in temperature is 75°C:

100°C - 25°C = 75°C

(Desired temp. - initial temp. = change in temp.)

Subbing these values into Q=mcΔT:

Q = 300g × 4.184J/g×°C × 75°C

Q = 94140J

Scientific notation tells us that we have two significant figures, so:

Q = 9.4 × 10⁴J

Answer:

Al(NO3)3 + Ca(OH)2 = Al(OH)3 + Ca(NO3)2.

Explanation:

The balanced equation for the reaction between calcium nitrate and aluminum hydroxide is: Ca(NO3)2 + 2Al(OH)3 → 2Al(NO3)3 + 3Ca(OH)2.

The balanced equation for the reaction between calcium nitrate and aluminum hydroxide is:

Ca(NO3)2 + 2Al(OH)3 → 2Al(NO3)3 + 3Ca(OH)2

In this reaction, calcium nitrate reacts with aluminum hydroxide to produce aluminum nitrate and calcium hydroxide.

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Answer:

North American X-15

Explanation:

This is the fastest manned aircraft

Answer: SR-71 Blackbird

Explanation: The fastest manned plane is the SR-71 Blackbird. It has traveled at 936 m/s. That is about three times the speed of sound, Mach 3. The SR-71 Blackbird set records both speed and altitude. (brainliest answer pls <3)

Answer:

16.56g.

Explanation:

You need to compare the number of coefficient of the reaction product to find how much water produced. The reaction formula will produce 6 carbon dioxide(CO2) and 6 water (H2O).

If the reaction produces 0.92 moles of carbon dioxide, then the amount of water produced in moles will be: 0.92 moles * (6/6)= 0.92 moles

The molar mass of water is 18g/mol, so the calculation of moles to mass will be: 0.92 moles * (18g/mol)= 16.56g.

Answer:

See the answer below, please.

Explanation:

The bonds formed between metals and nonmetals are called ionics. These occur between atoms with electronegativity difference. Example: NaCl (Sodium Chloride)

Instead, covalent bonds are formed between two nonmetals (one or more electron pairs are shared). Example: H202 (hydrogen peroxide).

In the case of metal formed bonds, they are called metallic.

Answer:

Carbon and oxygen are chemically bonded in it.

Explanation:

The other answer choices do not apply for compounds, but rather for mixtures instead.

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No matter where it was collected, carbon dioxide has a constant composition, making it a pure substance. One carbon atom and two oxygen atoms are always present in each carbon dioxide molecule. Thus, option A is correct.

Two oxygen atoms are covalently bound to one carbon atom to form the chemical molecule known as carbon dioxide (CO2). It exists as a gas in the Earth's atmosphere at standard pressure and temperature.

The production and burning of fossil fuels like coal, oil, and natural gas as well as during wildfires and other natural processes like volcanic eruptions.

Inhaling CO2 is thought to be only mildly harmful. The fundamental health impacts of CO2 are a result of its simple asphyxia nature.

A gas that decreases or replaces the natural oxygen in breathing air is referred to as a simple asphyxia. Mild CO2 exposure symptoms can include headache and sleepiness.

Therefore, Carbon and oxygen are chemically bonded in it.

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Answer: clouds and precipitation to form

Explanation: In a low pressure system warm air rises into the atmosphere and cools down and forms cloud. In low air pressure the humidity is high since there is enough space for water vapor to occupy causing precipitation.

Answer: an experiment is an empirical procedure that arbitrates competing models or hypotheses. Researchers also use experimentation to test existing theories or new hypotheses to support or disprove them.

Explanation: I don't know if this helps but if it does let me know.

Final answer:

Scientists perform experiments primarily to test hypotheses, gather data, and validate or disprove their proposed explanations for phenomena. These experiments are essential for the advancement of scientific knowledge and are often peer-reviewed and published if the results are significant.

Explanation:

The main reason scientists perform experiments is to test a hypothesis which is a proposed explanation for a phenomenon, and to answer specific research questions. Experiments are carefully designed to collect data and analyze results objectively. If the results support the hypothesis, further experiments may be conducted to test related hypotheses, or if the results are inconsistent with the hypothesis, it may be discarded for a new alternative hypothesis.

By performing experiments, scientists aim to ensure repeatability and to explore underlying causes for observed phenomena. Experiments are a critical aspect of the scientific method, enabling researchers to extend their knowledge of the natural universe through empirical evidence. The design of an experiment is guided by the goal to make measurements that test the hypothesis, and often involves statistical, mathematical, or graphical analysis of the data collected.

Significant results get published in scientific journals, which serve to communicate the findings and contribute to the body of scientific knowledge. With the advent of open access and electronic journal availability, the dissemination of scientific knowledge has become more accessible.

Answer:

Below.

Explanation:

1.   Al2(SO4)^3 (aq) + 6LiOH aql)  ----> 3Li2SO4 (aq) + 2Al(OH)^3 (s)

2.  (NH4)2CO3 (aq) + MgCl2 (aq)  ---->  2(NH4)Cl (aq) +  MgCO3 (s).

Chemical equations are represented using correct formulas and physical states, with the aluminum sulfate and lithium hydroxide reaction yielding aluminum hydroxide and lithium sulfate, and the ammonium carbonate and magnesium chloride reaction producing ammonium chloride and magnesium carbonate.

To convert word equations into chemical equations, it is essential to use correct chemical formulas and include the physical states of the compounds. Here are the given reactions converted into chemical equations:

Ensuring the reaction equations are balanced is crucial for accurately representing the conservation of mass in chemical reactions.

Answer:

A

Explanation:

The correct answer is B) The water molecules separate the crystals into molecules.

The smallest particle of a substance that has all of the physical and chemical properties of that substance. Molecules are made up of one or greater atoms.

Water dissolves in salt because the terrible part of a water molecule, the oxygen part is interested in the wonderful sodium ion of the salt. also, the effective part of the water molecule, the hydrogen component is drawn to the terrible chloride ion of the salt. Water molecules pull the sodium and chloride ions aside, breaking the ionic bond that held them together. After the salt compounds are pulled apart, the sodium and chloride atoms are surrounded via water molecules. once this occurs, the salt is dissolved, ensuing in a homogeneous solution.

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Answer:

it’s C

Explanation:

The role of a spark plug is to supply some of the energy of activation for the combustion reaction.

Explanation:

The correct answer is (C) The spark supplies some of the energy of activation for the combustion reaction, is  best describes the role of the spark from the spark plug in an automobile engine.

In an automobile engine, the spark from the spark plug plays a crucial role in initiating the combustion process. The combustion reaction involves the rapid oxidation of a fuel, typically a volatile hydrocarbon, which releases a significant amount of energy. However, this reaction requires an initial input of energy to overcome the energy barrier known as the activation energy.

The spark from the spark plug provides this necessary energy of activation. When the spark plug ignites, it creates a small, high-energy spark that is hot enough to initiate the combustion of the air-fuel mixture in the engine's cylinder. This spark raises the temperature of a small portion of the fuel-air mixture to a point where the molecules have enough kinetic energy to react with each other, thus starting the combustion reaction.

Once the reaction starts, it releases enough energy to sustain itself and continue the combustion process without additional input from the spark plug. The energy released by the combustion reaction is what powers the engine by pushing the pistons down, which in turn rotates the crankshaft and ultimately drives the vehicle's wheels.

To summarize, the spark from the spark plug is essential because it:

- Provides the energy of activation needed to initiate the combustion reaction.

- Does not decrease the energy of activation (option A).

- Does not significantly increase the concentration of the volatile reactant (option B).

- Does not alter the activated complex (option D), as the activated complex is a theoretical state in the reaction pathway, not something that can be provided or altered by external means.

- Does not provide the heat of vaporization (option E) for the hydrocarbon, as the spark's role is to initiate combustion, not to vaporize the fuel, although vaporization of the fuel is a necessary step before combustion.

Therefore, the spark's role is to supply some of the energy of activation for the combustion reaction, making option (C) the correct description.

Answer:

D. It will not have a nucleoid.

Explanation:

Cells with a nucleus are eukaryotic cells. This means they will have membrane-bound organelles. The nucleus is an example of a membrane bound organelle that houses the DNA.

A. It will not have nuclear membrane. - this is false, the nucleus is surrounded by the nuclear membrane

B. It will not have a nucleolus - this is false, the nucleolus is a part of the nucleus, usually where ribosomal RNAs are made

C. It will not have ribosomes - this is false, proteins are made in ribosomes and they are present in all cells

D. It will not have a nucleoid - this is true. The nucleoid is a space in the cytoplasm of prokaryotic cells that houses the DNA. It is not membrane bound, and is distinct from the nucleus.

Answer:

top answer is right for sur!

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Explanation:

Answer:

The first choice, [tex]-205.7\; \rm kJ[/tex].

Explanation:

Let the three reactions, where the enthalpy change were known, be called (1), (2), and (3).

The goal is to find the enthalpy change of the fourth equation. Assume that this equation can be written as [tex]x \times (1) + y \times (2) + z \times (3)[/tex] for some [tex]x[/tex], [tex]y[/tex], and [tex]z[/tex] (might not be whole numbers or take positive values.) Then, by Hess's Law, the enthalpy change of that reaction would be [tex]x \cdot \Delta H_1 + y \cdot \Delta H_2 + z \cdot \Delta H_3[/tex].

To find these [tex]x[/tex], [tex]y[/tex], and [tex]z[/tex], consider: what combination of reaction (1), (2), and (3) would give the fourth reaction?

Imagine that the coefficients are positive for all the reactants, and negative for all the products.

For example: in (1), [tex]\rm H_2\; (g)[/tex] has a coefficient of [tex]2[/tex]. However, since it is on the the product side of (1), its value should be [tex]-2[/tex]. Also, in (3)

Since there is no [tex]\rm H_2\; (g)[/tex] in the desired equation, the value of [tex]x[/tex], [tex]y[/tex], and [tex]z[/tex] should ensure that [tex]-2x + z = 0[/tex].

Another example: [tex]\rm CH_4\; (g)[/tex] is on the reactant side of the first reaction. Its coefficient in the equation is [tex]1[/tex], so that corresponds to [tex]+1[/tex]. Since [tex]\rm CH_4[/tex] is neither in (2) nor in (3), the value of

In the desired equation, [tex]\rm CH_4\; (g)[/tex] is on the reactant side with a coefficient of [tex]1[/tex]. As a result, the value of [tex]x[/tex], [tex]y[/tex], and [tex]z[/tex] should ensure that [tex]x = 1[/tex].

One such equation can be found for each species in the reactions.

[tex]\displaystyle \begin{cases}x = 1 & \left(\text{For $\mathrm{CH_4\; (g)}$}\right) \\ -x - y= 0 & \left(\text{For $\mathrm{C\; (s)}$}\right) \\ -2\, x + z = 0 & \left(\text{For $\mathrm{H_2\; (g)}$}\right) \\ y = -1 & \left(\text{For $\mathrm{CCl_4\; (g)}$}\right) \\ -2\, y + z= 4 & \left(\text{For $\mathrm{Cl_2\; (g)}$}\right) \\ -2\, z = -4 & \left(\text{For $\mathrm{HCl\; (g)}$}\right)\end{cases}[/tex].

Solve this system of equations for [tex]x[/tex], [tex]y[/tex], and [tex]z[/tex] (this approach works only if at least one solution exists.) In this case,

[tex]\displaystyle \begin{cases}x = 1 \\ y = -1 \\ z = 2\end{cases}[/tex].

Calculate the enthalpy change of the desired reaction:

[tex]\begin{aligned}\Delta H &= x\times \Delta H_1 + y \times \Delta H_2 + z \times \Delta H_3 \\ &= 1 \times 74.6 + (-1) \times 95.7 + 2 \times (-92.3) \\ &= -205.7\; \rm kJ\end{aligned}[/tex].

Answer:

Virtual images.

Hope this helps.

Write the balanced chemical equation.

Convert the units of the given substance (A) to moles.

Use the mole ratio to calculate the moles of wanted substance (B).

Convert moles of the wanted substance to the desired units.

Answer:

C

Explanation:

Answer: option C

Explanation:

A chlorine atom can form ionic bonds by accepting an electron and covalent bonds by sharing electrons

Answer:

17.85moles

Explanation:

Check attachment

Answer:

The same mass divided by a larger volume results in a smaller value for density. Therefore, liquid silver is less dense than solid silver. Temperature and solid density The density of solids usually decreases slightly as temperature increases because solids expand when heated.

Explanation:

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Liquid silver is less dense than solid silver due to the density between these two species.

It is defined as the ratio of mass over volume. The same mass divided by a larger volume results in a smaller value for density. Therefore, liquid silver is less dense than solid silver. The density of solids usually decreases slightly as temperature increases because solids expand when heated. The vibrations of the molecules increases, and it is easier for the molecules to slide past each other.

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Final answer:

Diamonds are considered a metamorphic rock because they are formed through intense heat and pressure deep within the Earth's mantle, which transforms carbon into a crystalline structure. Unlike other metamorphic rocks that show foliation, diamonds are non-foliated as they consist of a single mineral.

Explanation:

We consider diamonds a kind of metamorphic rock because they are formed deep within Earth's mantle through a process of intense heat and pressure. This process transforms the carbon atoms into a crystal structure known as a diamond. Metamorphism involves the recrystallization of minerals and can lead to the formation of new minerals, the reorientation of minerals due to pressure, and sometimes the migration of ions within crystal structures due to heat. While most metamorphic rocks are found in mountain belts or ancient mountain belts due to the conditions conducive to metamorphism, diamonds are actually formed at much greater depths and require unique conditions including temperatures around 900 to 1,300 degrees Celsius, and pressures over 45 kilobars.

The formation of metamorphic rocks, including diamonds, is a facet of the rock cycle, and these transformations allow rocks to become stable under new environmental conditions. Unlike most metamorphic rocks that exhibit foliation due to the reorientation of minerals, diamonds do not show foliation as they are a single mineral rock, thus they are considered non-foliated. They are created from a single element, carbon, and although they have a different formation process compared to foliated metamorphic rocks, the principles of temperature and pressure still apply in their creation.

As the ions present on a magnet and a superconductor are oppositely charged, it would help a superconductor to float over a magnet.

An ion is defined as an atom or a molecule which has a net electrical charge. There are 2 types of ions :1) cation 2) anion . The cation is the positively charged ion and anion is the negatively charged ion . As they are oppositely charged they attract each resulting in the formation of ionic bond.

Ions consisting of single atom are mono-atomic ions while which consists of two or more ions are called as poly-atomic ions . They are created by chemical interactions . They are very reactive in their gaseous state and rapidly react with oppositely charged ions resulting in neutral molecules.Ions of opposite charges attract in an ionic bond.

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Answer:

Ok so I seen your comment because I was looking up the answer and couldn’t find it anywhere so I risked to see if I got it wrong and got it right the answer is b on Plato and sorry I don’t know what it said but I do know I clicked on b hope this helps

Explanation:

Answer:

B.

The solution is nonviable because the time cannot be negative.

Explanation:

If it's wrong tell me

the atmosphere,the terrestrial biosphere, the oceans and the sediments