Answer:
Explanation:
<em>Endothermi</em>c processes absorb energy. The final state contains more energy than the initial state.
Since ice absorbs heat energy <em>in the process of completely melting</em> this is an <em>endothermic</em> process.
The process involves two stages: 1) heating the ice up to the melting point, which is 0ºC, and 2) melting the ice.
1. Heating the ice from -15ºC to 0ºC
a) Formula: Q = m×C×ΔT
- C = 2.108 kJ/kg.ºC (specific heat of ice)
b) Calculations:
- Q = m×C×ΔT = 1.6 kg × 2.108 kJ/kg.ºC × 15ºC = 50.592 kJ
2. Melting the ice at 0ºC
a) Formula: L = m × ΔHf
- ΔHf = 334 kJ/kg (latent heat of fussion)
b) Calculations
- L = m × ΔHf = 1.6 kg × 334 kJ/kg = 534.40 kJ
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<u>2. Total heat</u>
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- 50.592 kJ + 534.40 kJ = 584.992 kJ ≈ 590 kJ (rounded to 2 significant figures)
Answer:
A solution is made by dissolving 4.87 g of potassium nitrate in water to a final volume of 86.4 mL solution. The weight/weight % or percent by mass of the solute is :
<u>2.67%</u>
Explanation:
Note : Look at the density of potassium nitrate in water if given in the question.
<u><em>You are calculating </em></u><u><em>weight /Volume</em></u><u><em> not weight/weight % or percent by mass of the solute</em></u>
Here the <u>weight/weight % or percent by mass</u> of the solute is asked : So first convert the<u> VOLUME OF SOLUTION into MASS</u>
Density of potassium nitrate in water KNO3 = 2.11 g/mL

Density = 2.11 g/mL
Volume of solution = 86.4 mL



Mass of Solute = 4.87 g
Mass of Solution = 183.2 g
w/w% of the solute =


w/w%=2.67%
False everything involves matter
Answer:
1. B
2. D. the form of a substance changes but not its identity
3. C
4. D