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alisha [4.7K]
4 years ago
7

What is the ph of a solution of 0.650 m k2hpo4, potassium hydrogen phosphate?

Chemistry
1 answer:
Pie4 years ago
3 0

phosphate?

At 25 ∘C phosphoric acid, H3PO4, has the following equilibrium constants:

Ka1= 7.5×10^-3

Ka2= 36.2×10^−8

Ka3 = 4.2×10^−13

This is a question about the dissociation of weak polyprotic acids.

When pKas of polyprotic intermediates have a difference of 2 or more you just average them using the equation: pH = (pKa2 + pKa3) / 2

pKa2 = -log(Ka2) ; pKa3 = -log(Ka3)

So, for this problem, REGARDLESS OF THE SUPPLIED CONCENTRATION , the answer is:

pH = (7.2076+12.3767) / 2

pH = 9.79

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The rate of reaction was measured during a chemical reaction. After the first 3 seconds, the rate of reaction was 1.8 x10-6 M/s.
avanturin [10]

Answer:

The rate would be lower and the concentration of reactants would be lower.

Explanation:

The rate of a chemical reaction depends on the rate constant and the concentration of reactants.

For Ex:

For a reaction experimentally given by A + B ----> C + D

Rate = k[A][B]

where k is the rate constant

          [A] = concentration of reactant A

          [B] = concentration of reactant B

As the reaction proceeds,the concentration of reactant decrease and concentration of products increase.Rate constant k depends only on temperature and activation energy.Hence it will remain constant throughout the reaction assuming that reaction is carried out at constant temperature and pressure.

Hence rate will depend only on concentration of reactants and hence decrease with decrease in concentration of reactants.

8 0
3 years ago
What is the mass of 5.2 moles of Fe?
sashaice [31]

Answer:

279.225g

Explanation:

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3 years ago
The strength of an acid or a base is determined by the
Tresset [83]
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3 0
3 years ago
An object with a mass of 5.6 g raises the level of water in a graduated cylinder from 25.1 mL to 33.9 mL. What is the density of
kondor19780726 [428]

Answer:

0.6364 g/cm^3

Explanation:

Density = mass/volume

Where mass = 5.6g and...

Volume = (33.9 - 25.1) = 8.8ml

Where 1ml = 1 cm^3

Density = 5.6/8.8 = 0.6364 g/cm^3

6 0
3 years ago
Read 2 more answers
Use the amount (mol) of solute and amount (mol) of solvent to calculate the mole fraction. An aqueous solution of ethanol, CH3CH
Blizzard [7]

Answer:

%m/m = 0.9975%

Xₐ = 0.0039

Explanation:

In order to do this, we need various data. First to all, we need tje molecular mass of the ethanol. this can be obtained in handbooks, or simply taking the atomic weights of carbon (12 g/mol), Hydrogen (1 g/mol) and oxygen (16 g/mol) and summing those values:

MM C₂H₆O = (2*12) + (6*1) + (16*1) = 46 g/mol

Now, there is an expression that is commonly used to determine the molarity of a solution given the mass percent and density, and assuming of course, 1 liter of solution:

M = d * %m/m * 1000 / MM * 100     (1)

From here, we can solve for %m/m:

%m/m = M * MM * 100 / d * 1000

As the problem is not saying the volume of solution, we can easily assume we have 1 liter of solution. Therefore, the %m/m replacing the given data is:

%m/m = 0.216 *46 * 100 / 0.996 * 1000

<h2>%m/m = 0.9975%</h2>

To get the mole fraction, we first need to get the volume of solvent. From the density, we can get the mass of solution:

m = V * d

m = 1000 * 0.996 = 996 g of solution.

The mass of solute is:

m = 0.216 mol/L * 46 g/mol

m = 9.936 g/L, or simply we have 9.936 g of ethanol in 1 L of solution.

The mass of solvent:

solvent = 996 - 9.936 = 986.064 g

The molecular mass of water, so we can get the moles is 18 g/mol so:

moles water = 986.064 / 18 = 54.78

Finally the mole fraction:

Xₐ = 0.216 / (0.216 + 54.78)

<h2>Xₐ = 0.0039</h2>

Hope this helps

4 0
3 years ago
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