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Roman55 [17]
3 years ago
7

PLEASE HELP WITH THESE TWO QUESTIONS

Chemistry
1 answer:
adelina 88 [10]3 years ago
3 0

1. Q=112.8 kJ

2. Q=5.01 kJ

<h3>Further explanation</h3>

The heat required for phase change :

  • melting/freezing :

Q = mLf

Lf=latent heat of fusion

  • vaporization/condensation

Q = mLv

Lv=latent heat of vaporization

1.

m=50 g=0.05 kg

Lv (water) = 2256 kJ/kg

\tt Q=0.05\times 2256=112.8~kJ

2.

m=15 g=0.015 kg

Lf for water = 334 kj/kg

\tt Q=0.015\times 334=5.01~kJ

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What makes calcium and nitrogen different list two differences
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Answer:

the difference in electronegativity is so large (2.04) that the bonding electrons spend almost all their time on the nitrogen atom.

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A silver necklace has a density of 10.5 g/mL and a volume of 1.5 mL. What is the mass of the silver necklace?
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15.75g

Explanation:

Rearrange the formula: density = mass/volume, so that mass is the subject: mass = density × volume

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Using the Henderson - Hasselbalch equation;

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