# How many grams of oxygen reacted if 1320 kJ of heat was released?

January 20, 2021 | education

| Given:

Q1 = 1320 kJ

To find:

m (O2) -?

Decision:

1) Write down the equation of the thermochemical reaction:

S + O2 => SO2 + 440 kJ;

2) Make up the proportion and calculate the amount of substance O2:

440 kJ – 1 mol O2;

1320 kJ – (x) mol O2;

x = n (O2) = 1320 * 1/440 = 3 mol;

3) Using the periodic system of D.I.Mendeleev, calculate the molar mass of O2:

M (O2) = Mr (O2) = Ar (O) * N (O) = 16 * 2 = 32 g / mol;

4) Calculate the mass of O2:

m (O2) = n (O2) * M (O2) = 3 * 32 = 96 g.

Answer: O2 mass is 96 g

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