Question

How many moles of Ag+ ions are present in 10 ml of a 0.75 M AgNO3 solution?

a. 9.1 x 10^-3
b. 7.5 x 10^-3
c. 2.0 x 10^-2
d. 2.75 x 10^-2
e. 1.75 x 10^-2

Answer 1

b. 7.5 x 10^-3

Step-by-step explanation:

To solve this problem we need to keep in mind the definition of molarity:

• Molarity = moles of solute / liters of solution

With the above information in mind it is possible to calculate the moles of solute, given the volume (10 mL) and concentration (0.75 M) of the solution:

• First we convert 10 mL to L ⇒ 10 mL / 1000 = 0.01 L

Then we calculate the moles of AgNO₃:

• moles of solute = Molarity * Liters of solution

• 0.01 L * 0.75 M = 7.5x10⁻³ mol AgNO₃

One mole of AgNO₃ contains one mole of Ag⁺, thus the number of Ag⁺ moles is also 7.5x10⁻³.