Question

How many grams of HF are needed for 182 grams of SiO2 to react completely? Express your answer to three significant figures.

Answer 1

1) Check if the chemical equation is balanced.

`\text{SiO}_2+4HF\rightarrow SiF_4+2H_2O`

2) Convert grams of SiO2 into moles

`molesofSiO_2=182gSiO_2\cdot(1moleofSiO_2)/(60.0843gSiO_2)=3.0291`

3) How many moles of HF reacts

`\text{molesofHF}=3.0291molesofSiO_2\cdot\frac{4\text{molesofHF}}{1moleofSiO_2}=12.1163`

4) Convert moles of HF into grams

`\text{gramsofHF}=12.1163\text{molesofHF}\cdot\frac{20.0063\text{gof HF}}{1\text{moleofHF}}=242.4025\text{ g of HF}`

The reaction requires 242 grams of HF