Question

(a) Two of the simplest compounds containing just carbon and hydrogen are methane and ethane. Given that methane contains 0.3357 g hydrogen for every 1.00 g carbon and that the ratio of g hydrogen/1.OO g carbon in methane to g hydrogen/1.OO g carbon in ethane is 4:3, determine the number of grams of hydrogen per gram of carbon in ethane. (b) Xenon (Xe) and fluorine (F) can combine to form several different compounds, including XeF2, which contains 0.2894 g fluorine for every gram of xenon. Use the law of multiple proportions to determine n, which represents the number of F atoms in another compound, XeFn, given that it contains 0.8682 g of F for every gram of Xe.

Answer 1

(a) 0.2518 g; (b) 6

Step-by-step explanation:

The Law of Multiple Proportions states that when two elements A and B combine to form two or more compounds, the masses of B that combine with a given mass of A are in the ratios of small whole numbers.

That is, if one compound has a ratio r₁ and the other has a ratio r₂, the ratio of the ratios r is in small whole numbers.

(a) Methane and ethane

In methane, the mass ratio of H:C is r₁ = 0.3357:1.00.

In ethane, the mass ratio of H:C is r₂

The ratio of the ratios r = ⁴/₃

r = r₁/r₂

⁴/₃ = 0.3357/r₂

(⁴/₃)r₂ = 0.3357

r₂ = 0.3357 × ¾ = 0.2518:1

Ethane contains 0.2518 g of H for every 1 g of C.

(b) Xenon fluorides

In XeF₂, the mass ratio of F:Xe is r₁ = 0.2894:1

In XeFₙ, the mass ratio of F:Xe is r₂ = 0.8682:1

r = r₂/r₁ = 0.8682/0.2894 = 3.000:1 ≈ 3:1

XeFₙ contains three times as many F atoms as XeF₂.

n = 6