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
Explanation:
The enthalpy of a reaction for a chemical change can be determined by
Using the formula ∆H = m x s x ∆T to solve.
∆H is the change in the enthalpy of the reaction.
where, m, the mass of our reactants,
s, the specific heat of our product,
and ∆T, the temperature change during the reaction,
Thus, we are ready to calculate the enthalpy of reaction.
Simply we can put in values into the formula ∆H = m x s x ∆T and multiply to solve.
Answer:
Henderson Hasselbalch equation: pH = pKa + log [salt]/[acid]
You need to know the pKa for acetic acid. Looking it up one finds it to be 4.76
(a). pH = 4.76 + log [0.13]/[0.10]
= 4.76 + 0.11
= 4.87
(b) KOH + CH3COOH =>H2O + CH3COOK so (acid)goes down and (salt)goes up. Assuming no change in volume, you have 0.10 mol acid - 0.02 mol = 0.08 mol acid and 0.13 mol salt + 0.02 mol = 0.15 mol salt
pH = 4.76 + log [0.15]/[0.08]
= 4.76 + 0.27
= 5.03