Question

question 8 (5 points)
listen
h₂ + br₂ → 2hbr
if 2.23 g of hydrogen (h₂) reacts completely, how many grams of hydrogen bromide (hbr) is formed? (mw br=79.9)
a) 179 g of hbr
b) 2.21 g of hbr
c) 82.13 g of hbr
d) 80.92 g of hbr

Explanation:

Step1: Calculate moles of \( H_2 \)

Molar mass of \( H_2 = 2\times1 = 2 \, g/mol \).
Moles of \( H_2 = \frac{mass}{molar \, mass} = \frac{2.23 \, g}{2 \, g/mol} = 1.115 \, mol \).

Step2: Relate moles of \( H_2 \) to \( HBr \)

From the reaction \( H_2 + Br_2
ightarrow 2HBr \), 1 mol \( H_2 \) produces 2 mol \( HBr \).
Moles of \( HBr = 2 \times moles \, of \, H_2 = 2 \times 1.115 = 2.23 \, mol \).

Step3: Calculate molar mass of \( HBr \)

Molar mass of \( HBr = 1 + 79.9 = 80.9 \, g/mol \).

Step4: Calculate mass of \( HBr \)

Mass of \( HBr = moles \times molar \, mass = 2.23 \, mol \times 80.9 \, g/mol \approx 179 \, g \)? Wait, no—wait, recalculate moles: Wait, 2.23 g \( H_2 \) is \( \frac{2.23}{2} = 1.115 \) mol \( H_2 \). Then moles \( HBr = 2 \times 1.115 = 2.23 \) mol? Wait, no, wait the reaction is 1:2. Wait, no, 1 mol \( H_2 \) gives 2 mol \( HBr \). So 1.115 mol \( H_2 \) gives \( 2 \times 1.115 = 2.23 \) mol \( HBr \). Then molar mass \( HBr = 1 + 79.9 = 80.9 \, g/mol \). So mass \( HBr = 2.23 \times 80.9 \approx 179 \, g \)? Wait, but let's check again. Wait, 2.23 g \( H_2 \) is \( 2.23 / 2 = 1.115 \) mol. Then 1.115 mol \( H_2 \) produces \( 2 \times 1.115 = 2.23 \) mol \( HBr \). Molar mass \( HBr = 1 + 79.9 = 80.9 \, g/mol \). So 2.23 mol 80.9 g/mol = 2.23 80.9 ≈ 179 g. Wait, but option A is 179 g. Wait, but maybe I made a mistake. Wait, no—wait, 2.23 g \( H_2 \) is 1.115 mol. Then 2 mol \( HBr \) per 1 mol \( H_2 \), so 2.23 mol \( HBr \). Then 2.23 * 80.9 ≈ 179. So answer is A? Wait, but let's check the options. Option A is 179 g of HBr.

Wait, wait, no—wait, 2.23 g \( H_2 \) is \( 2.23 / 2 = 1.115 \) mol. Then moles \( HBr = 2 \times 1.115 = 2.23 \) mol. Molar mass \( HBr = 1 + 79.9 = 80.9 \) g/mol. So 2.23 80.9 = 2.23 80.9. Let's calculate 2 80.9 = 161.8, 0.23 80.9 ≈ 18.607, total ≈ 180.4, close to 179. Maybe rounding differences. So the answer should be A) 179 g of HBr.

Answer:

A) 179 g of HBr