Answer:
(a) 0.2518 g; (b) 6
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
Answer:
pH = 6.964 which rounds to 7.0 if 2 sig figs
Explanation:
Ka₁ * Ka₂ = x
2.4x10⁻⁴ * 4.9x10⁻¹¹ = 1.176x10⁻¹⁴
√1.176x10⁻¹⁴ = 1.084435337x10⁻⁷
pH= -log[H⁺]
pH= -log[1.084435337x10⁻⁷]
pH= 6.964796339
The mole fraction of urea in a solution that contain 2.1 mol Urea and 4.4 mole of water is 0.32
calculation
mole fraction = moles of urea/ total mole
moles of urea = 2.1 mole
calculate the total mole
= 2.1 mole + 4.4 mole = 6.5
Mole fraction is therefore = 2.1/.6.5 = 0.32