True or False Exam 3

Question 1

In an acidic solution at 25C, [H3O+] > 1.0 x10−7 M and pH > 7. Why?

Answer 1

False, it is lower than 7

Question 2

A solution with a pH of 2 has a hydronium ion, H3O+, concentration that is 30 times greater than that of a
solution of pH 5. Why?

Answer 2

False, its 30 times less since pH 2 is less than pH 5

Question 3

if the [H3O+] in an aqueous solution at 25C is less than 1.0 x 10−7 M, then the pH is greater than 7. Why?

Answer 3

True, because this is saying the H3O is reacting with water so then 7 so obviously the pH is greater than 7

Question 3

A Bronsted acid is a hydrogen ion donor. Why?

Answer 3

True because its the H+ and A- so it has to give an H.

Question 3

A conjugate acid/base pair differs by one H+ ion. Why?

Answer 3

True, because acid donates an H+ and makes its conj. base that way

Question 4

When comparing acids of equal concentration, the stronger the acid, the lower the pH of the solution. Why?

Answer 4

False, because its equal they are of equal concentration

Question 4

The weaker the acid, the lower the pH. Why?

Answer 4

False, weaker acid means a higher pH

Question 5

For a strong acid, the [H3O+] is approximately equal to the initial concentration of the acid. Why?

Answer 5

True, because they are both strong acids

Question 5

Compare 0.1 M H2SO3 to 0.1 M H2SO4. The pH of the H2SO3 solution is lower than the H2SO4 solution. Why?

Answer 5

False

Question 5

In an acidic solution at 25C, pOH > 7. Why?

Answer 5

True, because the acidic solution means a low pH and a high pOH

Question 6

A solution with pH of 1 is 1000 times more acidic than a solution with a pH of 4. Why?

Answer 6

False, they go by 10’s, so really 1 is 30 times less than 4

Question 6

A solution with a pH of 14 is 30 times more basic than a solution with a pH of 11. Why?

Answer 6

True, consider them 10 to the power of the numbers, 14-11= 3 so it is 30 times more basic.

Question 6

The higher the pOH of a solution, the weaker the acid (assuming equal concentrations). Why?

Answer 6

False, higher pOH means lower pHso stronger acid

Question 7

The concentration of H3O+ for CH3COOH is approximately equal to the initial concentration of the acid. Why?

Answer 7

False, because the initial concentration is a weak acid

Question 7

A substance with an [OH─-] equal to 1.0 X 10─8 must be acidic. Why?

Answer 7

True, because the pOH is 8 so the pH is around 4

Question 8

When a strong acid is added to a buffer solution, the pH of the solution increases. Why?

Answer 8

False, Ph decreases

Question 9

When F− is added to a hydrofluoric acid solution (HF), the solution’s pH decreases. Why?

Answer 9

False, Ph increases

Question 9

A strong base reacts with a buffer solution to produce OH–. Why?

Answer 9

False,bases dont react with a buffer solution

Question 10

When HCl is added to a buffer solution containing H2SO3 and NaHSO3 as the buffer components, the HCl will
react with the HSO3─ portion of the buffer. Why?

Answer 10

True, because we are trying to make H2SO3

Question 10

The stronger an acid, the weaker its conjugate base. Why?

Answer 10

True, because strong acids make weak bases

Question 11

Weak acids have conjugate bases that are weak. Why?

Answer 11

True, it cannot make a strong base since its already weak

Question 12

All salts are composed of metals bonded to nonmetals. Why?

Answer 12

False, some salts have no metals. it just ionic bonded to nonionic

Question 13

Strong acids have conjugate bases that are strong bases. Why?

Answer 13

False, the stronger the acid the weaker the base

Question 14

A buffer is a solution that prevents the pH from changing when a strong acid or base is added to the solution. Why?

Answer 14

False, it doesnt prevent it just assists in lowering the amount of change happening.

Question 15

A solution of NH3/NH4Cl would be an example of a buffer. Why?

Answer 15

True, its an ion bonded to a nonionic compound

Question 16

The reaction of HCl with the buffer solution HClO/NaClO would be:
HClO + HCl → Cl- + H2ClO+. Why?

Answer 16

False, because it would react to MAKE the HClO, so HCl+ CLO- instead!