A student has the following data recorded: final readings: 760. mm Hg, 6.0L, 197 'C. initial readings:

A 420 mL sample of a 0.100 M formate buffer, pH 3.75, is treated with 7 mL of 1.00 M KOH. What is the pH following this addition

Art [367]

Answer: The pH of the resulting solution will be 3.60

Explanation:

Molarity is calculated by using the equation:

$\text{Molarity}=\frac{\text{Moles}}{\text{Volume}}$ ......(1)

We are given:

Molarity of formic acid = 0.100 M

Molarity of potassium formate = 0.100 M

Volume of solution = 420 mL = 0.420 L (Conversion factor: 1 L = 1000 mL)

Putting values in equation 1, we get:

$\text{Moles of formic acid}=(0.100mol/L\times 0.420L)=0.0420mol$

$\text{Moles of potassium formate}=(0.100mol/L\times 0.420L)=0.042mol$

Molarity of KOH = 1.00 M

Volume of solution = 7 mL = 0.007 L

Putting values in equation 1, we get:

$\text{Moles of KOH}=(1mol/L\times 0.007L)=0.007mol$

The chemical equation for the reaction of formic acid and KOH follows:

$HCOOH+KOH\rightleftharpoons HCOOK+H_2O$

I: 0.042 0.007 0.042

C: -0.007 -0.007 +0.007

E: 0.035 - 0.049

Volume of solution = [420 + 7] = 427 mL = 0.427 L

To calculate the pH of the acidic buffer, the equation for Henderson-Hasselbalch is used:

$pH=pK_a+ \log \frac{\text{[conjugate base]}}{\text{[acid]}}$ .......(2)

Given values:

$[HCOOK]=\frac{0.049}{0.427}$

$[HCOOH]=\frac{0.035}{0.427}$

$pK_a=3.75$

Putting values in equation 2, we get:

$pH=3.75-\log \frac{(0.049/0.427)}{(0.035/0.427)}\\\\pH=3.75-0.146\\\\pH=3.60$

Hence, the pH of the resulting solution will be 3.60

6 0

3 years ago

A 1 liter solution contains 0.304 M acetic acid and 0.228 M sodium acetate. Addition of 0.114 moles of perchloric acid will:____

Papessa [141]

Answer:

Lower the pH slightly

Explanation:

A buffer is defined as the mixture between weak acid and conjugate base. In the problem, acetic acid is the weak acid and sodium acetate the conjugate base.

When a strong acid as perchloric acid is added to a buffer, the pH decreases slightly because the acid reacts with conjugate base producing weak acid and not affecting directly the concentration of H⁺ ions.

5 0

3 years ago

State one advantage of building a space station in orbit instead of sending it all up in one piece.

Anit [1.1K]

Building a space station in orbit is a safety measure. If a rocket fails to bring up the entire space station in one piece it would be extremely expensive to build a new one. Bringing it up in multiple places ensures less money would be lost if the rocket fails.

5 0

3 years ago

This is to observe carefully and in detail so as to identify causes, key factors, or possible results

lesantik [10]

To analyze. Oml they won't let me add it unless I write more. Smh.

3 0

4 years ago

Read 2 more answers

Which shows the correct order of steps during the formation of an ionic bond?

LuckyWell [14K]

Answer: c.

Electrons are transferred → Ions form → Ions are attracted to each other