Question

question 7 (5 points)
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how many moles of carbon tetrachloride (ccl₄) is represented by 543.2 g of carbon tetrachloride? the atomic weight of carbon is 12.01 and the atomic weight of chlorine is 35.45.
a) 8.35×10⁴ moles
b) 5.42 moles
c) 3.53 moles
d) 11.4 moles

Explanation:

Step1: Calculate molar mass of \( CCl_4 \)

Molar mass of \( CCl_4 \) = atomic weight of C + 4×atomic weight of Cl.
Atomic weight of C = 12.01, atomic weight of Cl = 35.45.
So, molar mass \( M = 12.01 + 4\times35.45 \)
\( M = 12.01 + 141.8 = 153.81 \, g/mol \).

Step2: Use moles formula \( n = \frac{m}{M} \)

Given mass \( m = 543.2 \, g \), molar mass \( M = 153.81 \, g/mol \).
\( n = \frac{543.2}{153.81} \approx 3.53 \, moles \)? Wait, no, wait: Wait, 543.2 divided by 153.81: Let's recalculate. 153.81×3 = 461.43, 543.2 - 461.43 = 81.77. 81.77/153.81 ≈ 0.53. Wait, no, wait, maybe I miscalculated molar mass? Wait, 4×35.45: 35.45×4 = 141.8. 141.8 + 12.01 = 153.81. Then 543.2 / 153.81: Let's do 543.2 ÷ 153.81. Let's see, 153.81×3 = 461.43, 543.2 - 461.43 = 81.77. 81.77 ÷ 153.81 ≈ 0.53. So total ≈ 3.53? Wait, but option C is 3.53. Wait, but wait, maybe I made a mistake. Wait, no, let's check again. Wait, 153.81 g/mol is molar mass. 543.2 g divided by 153.81 g/mol: 543.2 / 153.81 ≈ 3.53. So the answer is C? Wait, but wait, maybe I miscalculated molar mass. Wait, 35.45×4: 35×4=140, 0.45×4=1.8, so 141.8. 141.8 +12.01=153.81. Correct. Then 543.2 /153.81: Let's use calculator: 543.2 ÷ 153.81 ≈ 3.53. So option C is 3.53 moles.

Wait, but wait, the options: A is 8.35e4, B is 5.42, C is 3.53, D is 11.4. So according to calculation, it's 3.53, so option C.

Answer:

C) 3.53 moles