Answer: 0.028 grams
Explanation:
Depression in freezing point :
Formula used for lowering in freezing point is,

or,

where,
= change in freezing point
= freezing point constant (for benzene} =
m = molality
Putting in the values we get:


0.028 grams of DDT (solute) must be dissolved in 209.0 grams of benzene to reduce the freezing point by 0.400°C.
Answer:
24 mol Cu
General Formulas and Concepts:
<u>Chemistry</u>
Explanation:
<u>Step 1: Define</u>
RxN: 2Cu (s) + O₂ (g) → 2CuO (s)
Given: 12 moles O₂
<u>Step 2: Stoichiometry</u>
<u />
= 24 mol Cu
<u>Step 3: Check</u>
<em>We are given 2 sig figs.</em>
Our final answer is in 2 sig figs, so no need to round.