Amount of substance and the mole - 3.1 - (2)

Question 1

What does the molar mass, M, give a convenient way for?

Answer 1

linking moles with mass for any chemical substance

Question 2

What does the molar mass give?

Answer 2

it gives the mass in grams in each mole of the substance

Question 3

What is the molar mass?

Answer 3

it is the mass per mole of a substance

Question 4

What are the units of molar mass?

Answer 4

g mol^-1

Question 5

By what equation is the amount of substance (n), mass (m), and molar mass (M), linked by?

Answer 5

amount (n) = mass (m) / molar mass (M), OR, n = m/M

Question 6

Example 1: Calculate the amount of substance, in moles, in 96.0g of carbon, C

Answer 6

n = m / M = 96.0 / 12.0 = 8.0mol

Question 7

Example 2: Calculate the mass, in g, of 0.050 mol of NO2

Answer 7

rearrange n = m / M = n x M = 0.050 x 46.0 = 2.3g

Question 8

Example 3: Calculate the molar mass when 2.65g contains 0.025mol of a substance

Answer 8

n = m / M —> rearrange: M = m / n = 2.65 / 0.025 = 106.0g mol^-1