Question

part b: mass-to-mole

1. how many moles are in 36.04 g of water (h2o)?
2. convert 23.38 g of sodium chloride (nacl) to moles.
3. a sample contains 88.02 g of carbon dioxide (co2). how many moles are present?
4. determine the number of moles in 8.02 g of methane (ch4).
5. how many moles are in 44.8 g of oxygen gas (o2)?

Explanation:

Question 6:

Step1: Find molar mass of \(H_2O\)

Molar mass of \(H = 1.008\space g/mol\), \(O = 16.00\space g/mol\).
Molar mass of \(H_2O = 2\times1.008 + 16.00 = 18.016\space g/mol\).

Step2: Use mass - mole formula

Moles \(=\frac{\text{Mass}}{\text{Molar Mass}}\).
Mass \(= 36.04\space g\), Molar Mass \(= 18.016\space g/mol\).
Moles \(=\frac{36.04}{18.016}\approx2\space mol\).

Step1: Find molar mass of \(NaCl\)

Molar mass of \(Na = 22.99\space g/mol\), \(Cl = 35.45\space g/mol\).
Molar mass of \(NaCl = 22.99 + 35.45 = 58.44\space g/mol\).

Step2: Use mass - mole formula

Moles \(=\frac{\text{Mass}}{\text{Molar Mass}}\).
Mass \(= 23.38\space g\), Molar Mass \(= 58.44\space g/mol\).
Moles \(=\frac{23.38}{58.44}\approx0.4\space mol\) (rounded to one decimal place, more accurately \(\approx0.40\space mol\)).

Step1: Find molar mass of \(CO_2\)

Molar mass of \(C = 12.01\space g/mol\), \(O = 16.00\space g/mol\).
Molar mass of \(CO_2 = 12.01+2\times16.00 = 44.01\space g/mol\).

Step2: Use mass - mole formula

Moles \(=\frac{\text{Mass}}{\text{Molar Mass}}\).
Mass \(= 88.02\space g\), Molar Mass \(= 44.01\space g/mol\).
Moles \(=\frac{88.02}{44.01}=2\space mol\).

Answer:

\(2\space mol\)

Question 7: