Potassium nitrate decomposes when heated, forming potassium nitrite and oxygen gas.?

Question

a. Write a balanced chemical equation for this reaction.
b. What mass of KNO3 would be need to produce 18.4 liters of oxygen gas measured at 775 mmHg and 15 degrees Celsius.
c. What mass of KNO2 would also be produced?

Answer 1

Atomic weights: K=39 N=14 O=16 KNO3=101 KNO2=85

a. 2KNO3 ===> 2KNO2 + O2

b. 18.4LO2 x 775mmHg/760mmHg x 288K/273K x 1molO2/22.4LO2 x 2molKNO3/1molO2 x 101gKNO3/1molKNO3 = 178g KNO3

c. 18.4LO2 x 775mmHg/760mmHg x 288K/273K x 2molKNO2/1molO2 x 85gKNO2/1molKNO2 =

Answer 2

a) 2 KNO3 --> 2 KNO2 + O2 b) First, you will use the ideal gas law (PV = nRT) to calculate the moles of oxygen gas under those conditions. You will need to convert your pressure to atm and your temperature to K before plugging them into the equation. Once you have moles of O2 formed, you can use the coefficients in the balanced equation to calculate moles of KNO3, and then use its molar mass to calculate grams of KNO3. c) From the moles of O2, you can again use the coefficients of the balanced equation to calculate moles of KNO2 produced and then convert that to grams using the molar mass of KNO2. Hope this helps...