We read your photo as:

Potassium nitrate decomposes on heating, producing potassium oxide and gaseous nitrogen and oxygen: 4KNO3(s) → 2K2O(s) + 2N2(g) + 5O2(g). To produce 56.6 kg of oxygen, how many (a) moles of KNO3 and (b) grams of KNO3 must be heated?

Chemistry

ScanSolve AI Answer

Answers

2 parts
a

1.42×103 mol KNO3\text{1.42} \times 10^3 \text{ mol KNO}_3

b

1.43×105 g KNO3\text{1.43} \times 10^5 \text{ g KNO}_3

Step-by-step solution

4 steps

To solve this problem, we need to use stoichiometry based on the given balanced chemical equation:

4KNO3(s)→2K2O(s)+2N2(g)+5O2(g)4\text{KNO}_3\text{(s)} \rightarrow 2\text{K}_2\text{O(s)} + 2\text{N}_2\text{(g)} + 5\text{O}_2\text{(g)}

We are given that 56.6 kg of oxygen (O2\text{O}_2) is produced.

First, we need the molar masses:
Molar mass of O2=2×16.00 g/mol=32.00 g/mol\text{O}_2 = 2 \times 16.00 \text{ g/mol} = 32.00 \text{ g/mol}
Molar mass of KNO3=39.10 g/mol (K)+14.01 g/mol (N)+(3×16.00 g/mol (O))=101.11 g/mol\text{KNO}_3 = 39.10 \text{ g/mol (K)} + 14.01 \text{ g/mol (N)} + (3 \times 16.00 \text{ g/mol (O)}) = 101.11 \text{ g/mol}

Part a· 3 steps

Moles of KNO3\text{KNO}_3 must be heated

  1. Convert the mass of oxygen from kilograms to grams.

    Mass of O2=56.6 kg×1000 g1 kg=56600 g\text{Mass of O}_2 = 56.6 \text{ kg} \times \frac{1000 \text{ g}}{1 \text{ kg}} = 56600 \text{ g}

  2. Calculate the moles of oxygen produced.

    Moles of O2=Mass of O2Molar mass of O2=56600 g32.00 g/mol=1768.75 mol\text{Moles of O}_2 = \frac{\text{Mass of O}_2}{\text{Molar mass of O}_2} = \frac{56600 \text{ g}}{32.00 \text{ g/mol}} = 1768.75 \text{ mol}

  3. Use the mole ratio from the balanced equation to find the moles of KNO3\text{KNO}_3.

    From the equation, 4 moles of KNO3\text{KNO}_3 produce 5 moles of O2\text{O}_2.

    Moles of KNO3=1768.75 mol O2×4 mol KNO35 mol O2=1415 mol KNO3\text{Moles of KNO}_3 = 1768.75 \text{ mol O}_2 \times \frac{4 \text{ mol KNO}_3}{5 \text{ mol O}_2} = 1415 \text{ mol KNO}_3

    Rounding to three significant figures:

    1.42×103 mol KNO3\boxed{\text{1.42} \times 10^3 \text{ mol KNO}_3}

Part b

1.43×105 g KNO3\text{1.43} \times 10^5 \text{ g KNO}_3

Grams of KNO3\text{KNO}_3 must be heated

  1. Use the moles of KNO3\text{KNO}_3 calculated in part (a) and its molar mass to find the mass in grams.

    Mass of KNO3=Moles of KNO3×Molar mass of KNO3\text{Mass of KNO}_3 = \text{Moles of KNO}_3 \times \text{Molar mass of KNO}_3 Mass of KNO3=1415 mol×101.11 g/mol=143080.65 g\text{Mass of KNO}_3 = 1415 \text{ mol} \times 101.11 \text{ g/mol} = 143080.65 \text{ g}

    Rounding to three significant figures:

    1.43×105 g KNO3\boxed{\text{1.43} \times 10^5 \text{ g KNO}_3}
Was this helpful?

Try one yourself

A new problem that tests the same skill.

Still stuck on this one?

Ask a follow-up, and the answer starts from this question.

Got a different question?Ask your own question

More Chemistry Questions

QGiven Kc1 = 6.8 imes 10⁻⁴⁹ for NO2(g) ightleftharpoons NO(g) + O(g) and Kc2 = 5.8 imes 10⁻³⁴ for…QA) For the reaction N2(g) + 2O2(g) 2NO2(g):QDinitrogen tetraoxide, N2O4(g), decomposes to nitrogen dioxide, NO2(g), in a sealed syringe of…QA) Complete the diagram below to show how the product from heating sodium nitrate can be collected…QI) The reaction 2NO(g) + O2(g) -> 2NO2(g) involves a change in the number of moles of gas (3 moles…
See all Chemistry questions →
Got a syllabus? Photograph it and I'll tell you what's due and what's worth the most.