Question

Upon decomposition, one sample of magnesium fluoride produced 1.65 kg of magnesium and 2.57 kg of fluorine. A second sample produced 1.36 kg of magnesium.

How much fluorine (in grams) did the second sample produce?

A solution of ammonia and water contains 3.20×10²⁵ water molecules and 8.30×10²⁴ ammonia molecules. How many total hydrogen atoms are in this solution?

Answer 1

1)

mass of F / mass of Mg = same for all samples

mass of F in sample 2 / mass of Mg in sample 2 = mass of F in sample 1 / mass of Mg in sample 1

mass of F in sample 2 / 1.36 = 2.57 / 1.65

mass of F in sample 2 = 2.118 kg

mass of fluorine in second sample = 2.12 x 10^3 g

2)

since there are two H atoms in H2O and 3 hydrogen atoms in NH3

total no of Hyderogens = 2 x number of H2O + 3 x number of NH3

                                    = 2 x 3.2 x 10^25 + 3 x 8.30 x 10^24

total no of Hyderogens = 8.89 x 10^25