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2 years ago

What is the best buffer at pH = 5.0? Justify your answer.

Chemistry

1 answer:

Leona [35]2 years ago

4 0

Answer:

b) acetic acid (pKa = 4.76)

Explanation:

Considering the Henderson- Hasselbalch equation for the calculation of the pH of the buffer solution as:

pH=pKa+log[base]/[acid]

The weak acid for making the buffer must have a pKa value near to the desired pH of the weak acid.

So, near to value, pH = 5, acetic acid is close which have of pKa of 4.76

Thus, option B is correct.

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Gala2k [10]

Answer:

Question 1: D

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Question 3: A

Question 4: A

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3 years ago

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morpeh [17]

Answer:

Atoms are indivisible

I had a hard time finding this out.

Explanation: Dalton's atomic theory was the first complete attempt to describe all matter in terms of atoms and their properties. Dalton based his theory on the law of conservation of mass and the law of constant composition. The first part of his theory states that all matter is made of atoms, which are indivisible.

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2 years ago

A chemistry student weighs out of hypochlorous acid into a volumetric flask and dilutes to the mark with distilled water. He pla

riadik2000 [5.3K]

Answer:

Volume of NaOH, aka V2 = 6.32 mL to 3 sig. fig.

A chemistry student weighs out 0.0941 g of hypochlorous acid (HClo) into a 250. ml. volumetric flask and dilutes to the mark with distilled water. He plans to titrate the acid with 0.2000 M NaOH solution. Calculate the volume of NaOH solution the student will need to add to reach the equivalence point. Round your answer to 3 significant digits mL.

Explanation:

1 mole HClO = 74.44g

0.0941g = $\frac{0.0941}{74.44}$ = 0.00126 moles

Concentration = no. of moles/volume in L

Hence, Concentration of HClO = 0.00126/ 0.250L

= 0.005M.

C1V1 =C2V2

0.005 × 250 mL = 0.2 × V2

Volume of NaOH, aka V2 = 6.32 mL to 3 sig. fig.

3 0

2 years ago

Looking at the following equation, what coefficient should be placed in front of the H2? Fe + H2SO4 --> Fe2(SO4)3 + H2

Hatshy [7]

Answer:

3 (three)

Explanation:

2 Fe + 3H2SO4 = Fe2(SO4)3 + 3 H2 (basically just balance both sides)

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3 years ago

Calculate the molality of a solution that contains 51.2 g of naphthalene, C10H8, in 500 mL of carbon tetrachloride. The density

PtichkaEL [24]

Answer: The molality of naphthalene solution is 0.499 m

Explanation:

Density is defined as the ratio of mass and volume of a substance.

$\text{Density}=\frac{\text{Mass}}{\text{Volume}}$ ......(1)

Given values:

Volume of carbon tetrachloride = 500 mL

Density of carbon tetrachloride = 1.60 g/mL

Putting values in equation 1, we get:

$\text{Mass of carbon tetrachloride}=(1.60g/mL\times 500mL)=800g$

Molality is defined as the amount of solute expressed in the number of moles present per kilogram of solvent. The units of molarity are mol/kg. The formula used to calculate molarity:

$\text{Molality of solution}=\frac{\text{Given mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Mass of solvent (in g)}}$ .....(2)

Given values:

Given mass of naphthalene = 51.2 g

Molar mass of naphthalene = 128.17 g/mol

Mass of solvent = 800 g

Putting values in equation 2, we get:

$\text{Molality of naphthalene}=\frac{51.2\times 1000}{128.17\times 800}\\\\\text{Molality of naphthalene}=0.499m$

Hence, the molality of naphthalene solution is 0.499 m

4 0

2 years ago