Chemistry pH Calculations Quiz

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Questions and Answers

What is the primary focus of biochemistry?

The interaction between different animal species

The study of chemical processes in living organisms (correct)

The evolution of species

The study of human anatomy

Which of the following biological macromolecules is NOT mentioned in the context of biochemistry?

Enzymes (correct)

Nucleic acids

Proteins

Lipids

Why is water considered an ideal biological solvent?

It has a high boiling point

It can facilitate biochemical reactions (correct)

It is the most abundant liquid on Earth

It can dissolve any substance

Which two elements form the water molecule?

Hydrogen and oxygen Signup and view all the answers

What role do buffers play in biological systems?

They help maintain the pH of a solution Signup and view all the answers

Which statement about acids and bases reflects the Brønsted–Lowry theory?

Acids are substances that lose protons Signup and view all the answers

What shape does a water molecule resemble?

Skewed tetrahedron Signup and view all the answers

In which field is biochemistry NOT typically applied?

Psychology Signup and view all the answers

What characterizes a strong base?

It completely ionizes in water. Signup and view all the answers

Which of the following is a Brønsted-Lowry acid?

Hydrochloric acid Signup and view all the answers

What happens to a proton (H+) in water according to the provided content?

It becomes a hydronium ion (H3O+). Signup and view all the answers

Which of the following is NOT a strong base?

NH3 Signup and view all the answers

What indicator turns pink in the presence of a base?

Phenolphthalein indicator Signup and view all the answers

In the Brønsted-Lowry concept, what role does water play when it accepts a proton from hydrochloric acid?

Base Signup and view all the answers

Which statement regarding strong electrolytes is true?

They dissociate completely in solution. Signup and view all the answers

What is the process called when a Brønsted-Lowry acid donates a proton to a base?

Protonation Signup and view all the answers

What is the primary characteristic of a strong acid?

It completely ionizes in water. Signup and view all the answers

Which of the following is NOT a property of acids?

They release hydroxide ions in solution. Signup and view all the answers

Which compound is an example of a strong base?

LiOH Signup and view all the answers

What property allows water to act as a transport medium?

Solvent properties. Signup and view all the answers

Which of the following ions are produced when hydrogen chloride dissolves in water?

H+ and Cl- Signup and view all the answers

Which group of metals primarily forms Arrhenius bases?

Groups 1A and 2A metals. Signup and view all the answers

What is the role of water in temperature regulation within biological systems?

It has a high specific heat capacity. Signup and view all the answers

Why do acids produce a sour taste?

Because they release H+ ions. Signup and view all the answers

What is the pH value of a solution with a hydronium ion concentration of $1.0 \times 10^{-2} \ M$?

2.00 Signup and view all the answers

How does pH change in relation to hydronium ion concentration?

pH decreases as [H3O+] increases. Signup and view all the answers

If solution A has a pH of 2.00, which of the following solutions has a 10x lower [H3O+] concentration than solution A?

pH 3.00 Signup and view all the answers

What is the pOH of a solution with a hydronium ion concentration of $4.0 \times 10^{-3} \ M$?

11.00 Signup and view all the answers

In a buffered solution, what role does the acid play when a base is added?

Neutralizes the added base. Signup and view all the answers

What must be true about the acid and base present in a buffer solution?

They must not be able to neutralize each other. Signup and view all the answers

What is the pH of a solution with a hydronium concentration of $5 \times 10^{-8} \ M$?

7.30 Signup and view all the answers

What is the hydronium ion concentration in a solution with a pH of 4.00?

$1.0 \times 10^{-4} \ M$ Signup and view all the answers

What is the primary characteristic of buffer solutions?

They maintain a constant pH despite added acids or bases. Signup and view all the answers

Which combination can create a buffer solution?

HF, a weak acid, and NaF. Signup and view all the answers

Which statement about the Henderson-Hasselbalch equation is true?

It determines the pH of a buffer solution. Signup and view all the answers

What is the normal pH range of arterial blood?

7.35 – 7.45. Signup and view all the answers

What effect does a pH below 6.8 have on cells?

It disrupts proper cellular function and may result in death. Signup and view all the answers

In the buffer solution consisting of 0.15mol NH4Cl and 1.5mol NH3, what is being calculated?

The pH of the solution. Signup and view all the answers

Why are buffer solutions important in biological systems?

They maintain a stable pH essential for various biochemical processes. Signup and view all the answers

Which component is NOT typically part of a buffer solution?

Strong acid. Signup and view all the answers

Study Notes

pH Equation

pH is calculated using the equation: pH = -log[H3O+]
For example: pH = -log[1.0×10−2] = 2.00
pH is a logarithmic scale: A change of one pH unit corresponds to a tenfold change in [H3O+]

pH Solutions

Solution A: pH = 2.00
Solution B: pH = 3.00
Solution C: pH = 4.00
Solution A has a [H3O+] concentration 10x higher than B and 100x higher than C.

Calculating pH

To determine the pH of solutions:
- [H3O+] = 1.0×10−5 M
- [H3O+] = 5 × 10−8 M

Calculating pH & pOH

The [H3O+] concentration in a solution is 4.0×10−3 M
- Calculate the pH of the solution.
- Calculate the pOH of the solution.
The [OH−] concentration in a solution is 5.3×10−4 M.
- Calculate the pOH of the solution.
- Calculate the pH of the solution.

Buffers

A buffer solution maintains the pH of a solution by neutralizing added acid or base.
To achieve this, a buffer contains an acid to react with added OH− and a base to react with added H3O+.
The acid and base must not be able to neutralize each other.
Most buffer solutions consist of nearly equal concentrations of:
- Weak Acid and the Salt Containing its Conjugate Base
- Weak Base and the Salt Containing its Conjugate Acid

Henderson-Hasselbalch Equation

This equation can be used to calculate the pH of a buffer solution.

Sample Problem

What is the pH of a solution consisting of 0.75M H𝐶2𝐻3𝑂2 and 0.50M 𝑁𝑎𝐶2𝐻3𝑂2?

Exercise

What is the pH of a solution consisting of 0.15mol 𝑁𝐻4𝐶𝑙 and 1.5mol N𝐻3?
The Kb of 𝑁𝐻3 is 1.8𝑥10−5.

Buffers in Blood

Normal arterial blood pH ranges from 7.35–7.45.
If the pH falls below 6.8 or rises above 8.0, cells cannot function properly and death may result.

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Description

Test your understanding of pH calculations and the concepts related to hydronium ion concentration. This quiz covers topics such as logarithmic scales, the relationship between pH and pOH, and the role of buffer solutions in maintaining pH balance. Ideal for chemistry students looking to solidify their knowledge of acid-base chemistry.