Question

Question 23

25.00 cm³ of a 0.7892 mol.dm^-3 solution of potassium hydroxide is transferred to an empty 350.00 cm³ volumetric flask. This flask is made up to the mark with distilled water and then shaken well. The concentration of the potassium hydroxide in this second flask is:

a. 0.01109 mol.dm^-3

b. 0.05637 mol.dm^-3

c. 0.7892 mol.dm^-3

d. 17.74 mol.dm^-3

e. None of the above.

Question 24

What is the molarity of glacial acetic acid (CH₃COOH, Mr = 60.05 g/mol) at 25°C given that the density of acetic acid at that temperature is 1.049 g/mL?

a. 0.0174 M

b. 0.057 M

c. 57.2 M

d. 60.1 M

e. None of the above

 Question 25

Calculate the molarity of a KF (aq) solution containing 116.2 g of KF in 3.00 L of solution?

a. 0.02585 M

b. 0.667 M

c. 38.7 M

d. 58.1 M

e. None of the above

Answer 1

23.

n(KOH)= C_M * V = 0,7892 * 0,025 = =0,01973mol

C_M = n/V = 0,01973mol / 0,35 l= 0,05637 M

Answer: B

24.

V=m/p=60,05/1,049 =57,245 ml =0,057245 l

C_M = n / V = 1mol / 0,057245 l = 17,47 mol/l

Amswer: E

25.

M(KF) = 58 g/mol

n = m / M = 116,2 / 58 = 2mol

C_M = n / V = 2mol / 3 l = 0,667 M

Answer: B