1.- Compounds A (Cs = 0.35 J/g. o C), B (Cs = 0.90 J/g. o C) and C (Cs = 0.72 J/
ID: 809750 • Letter: 1
Question
1.- Compounds A (Cs = 0.35 J/g.oC), B (Cs = 0.90 J/g.oC) and C (Cs = 0.72 J/g.oC) have the same mass and same temperature. If the temperature of all three compounds (A, B and C) is decreased by 30 oC, which compound would loose the highest amount of energy?
a) All three would loose the same amount of energy
b) B
c) C
d) A
2.
Titanium (Ti) reacts with iodine (I2) to form titanium(III) iodide, emitting 839 kJ of heat. Determine the masses of titanium (if reacted with excess of iodine) if 1.55 x 103 kJ of heat is emitted by the reaction.
a) 5.34 g
b) 6.46 kg
c) 1.41 kg
d) 0.177 kg
3.
Substances, A and B have the same mass and specific heat. Substance A is at 50 oC and Substance B is at 20 oC. When both substances come in contact with each other, what would be the equilibrium temperature?
a) ~ 35 oC
b) ~ 0 oC
c) ~ 25 oC
d) ~ 45 oC
4.
Given the following reactions
Explanation / Answer
1 - b) B
2 - d) 0.177 kg
Divide 1.55 x 103 kJ / 839 kJ = 1.883
You need 2 * 1.84 moles Ti and 3 * 1.84 moles I2. Multiply by their atomic/molecular masses to get the mass of each required.
3 -
ms(t-20) = ms(50-t)
2t = 70
t = 35
4 -
2 NOCl(g) ? N2(g) + O2(g) + Cl2(g)
delta H = 2 x 38.6 kJ + 2 x - 90.3 kJ
= 107.4 kJ
5 -
Write the target equation and the equation for the combustion of glucose. We want to calculate the heat of formation of glucose, so our target equation will be: 6 C (s) + 3 O2 (g) + 6 H2 (g) ? C6H12O6 (s) ?H
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