Question

The nitrates of beryllium calcium magnesium and strontium all decompose in the same way when heated. When 2.00g of one of these anhydrous nitrates is decomposed, 1,32g of gas is produced. What is the nitrate?

Answer 1

The nitrates of beryllium calcium magnesium and strontium all decompose in the same way when heated.

When 2.00g of one of these anhydrous nitrates is decomposed, 1.32g of gas is produced.

Therefore the nitrate I would suppose is that of calcium. Calcium Nitrate.

         equation is 2Y(NO3)2(s) ⇒ 2MnO(s) + 4NO2(g) + O2(g)  

            Y(NO3)3 =2.00g                                  No2= x            O2 =1.32-x  

 

The mole ratio of NO2 to O2 is 4:1

(x/46.0) / ((1.32-x)/32) = 4  

x = 1.12  

1.12g of NO2 is produced

Molar mass of of the metal nitrate  

2.00g / 0.0122 mol = 164.3 g/mol  

Molar mass = x + 28 + 96 = 164.3  

x = 40.3

This is is the molar mass of calcium  

Hence,the metal nitrate is Ca(NO3)2.