11. The least chemically reactive of the hydrocarbon

Acetic acid has a pKa of 4.74. Buffer A: 0.10 M HC2H3O2, 0.10 M NaC2H3O2 Buffer B: 0.30 M HC2H3O2, 0.30 M NaC2H3O2 Buffer C: 0.5

e-lub [12.9K]

Answer:

Buffer B has the highest buffer capacity.

Buffer C has the lowest buffer capacity.

Explanation:

An effective weak acid-conjugate base buffer should have pH equal to $pK_{a}$ of the weak acid. For buffers with the same pH, higher the concentrations of the components in a buffer, higher will the buffer capacity.

Acetic acid is a weak acid and $CH_{3}COO^{-}$ is the conjugate base So, all the given buffers are weak acid-conjugate base buffers. The pH of these buffers are expressed as (Henderson-Hasselbalch):

$pH=pK_{a}(CH_{3}COOH)+log\frac{[CH_{3}COO^{-}]}{[CH_{3}COOH]}$

$pK_{a}(CH_{3}COOH)=4.74$

Buffer A: $pH=4.74+log(\frac{0.10}{0.10})=4.74$

Buffer B: $pH=4.74+log(\frac{0.30}{0.30})=4.74$

Buffer C: $pH=4.74+log(\frac{0.10}{0.50})=4.04$

So, both buffer A and buffer B has same pH value which is also equal to $pK_{a}$ . Buffer B has higher concentrations of the components as compared to buffer A, Hence, buffer B has the highest buffer capacity.

The pH of buffer C is far away from $pK_{a}$ . Therefore, buffer C has the lowest buffer capacity.

6 0

3 years ago

2. Calculate the mass of K in 90g of KOH

ValentinkaMS [17]

KOH = 90g

KOH = 57 g/mol

K = 40g/mol

57g/mol contains 90 g

40g/mol will contain?

= 63.15 g

The mass of K is 63.15g

8 0

2 years ago

Which component of the dri reflects the requirement of a nutrient for 50 percent of healthy americans and canadians in a specifi

grandymaker [24]

The component of the dri reflects the requirement of a nutrient for 50 percent of healthy americans and canadians in a specific life stage and gender is Estimated Average Requirement (EAR).

What is EAR?

A daily food intake number known as the Estimated Average Requirement (EAR) is one that is thought to satisfy the needs of 50% of healthy persons in a given life stage and gender group.

Based on a review of the scientific literature, the estimated average requirements (EAR) are predicted to meet the needs of 50% of the population in that age range.

It serves as the foundation for the creation of RDAs and is employed to assess the sufficiency of nutritional consumption for a given population.

To learn more about EAR click the given link

brainly.com/question/14449512

#SPJ4

6 0

1 year ago

Two moles of magnesium (Mg) and five moles of oxygen (O2) are placed in a reaction vessel. When magnesium is ignited, it reacts

SOVA2 [1]

Answer:

$\boxed{\text{Mg is the limiting reactant}}$

Explanation:

We are given the amounts of two reactants, so this is a limiting reactant problem.

We know that we will need moles, so, lets assemble the data in one place.

2Mg + O₂ ⟶ 2MgO

n/mol: 2 5

Calculate the moles of MgO we can obtain from each reactant.

From Mg:

The molar ratio of MgO:Mg is 2:2

$\text{Moles of MgO} = \text{2 mol Mg} \times \dfrac{\text{2 mol MgO}}{\text{2 mol Mg}} = \text{2 mol MgO}$

From O₂:

The molar ratio of MgO:O₂ is 2:1.

$\text{Moles of MgO} = \text{5 mol O}_{2} \times \dfrac{\text{2 mol MgO}}{\text{1 mol O}_{2}} = \text{10 mol MgO}\\\\\boxed{\textbf{Mg is the limiting reactant}} \text{ because it gives the smaller amount of MgO}$