I only need help with the bolded questions. If the student measured the initial
ID: 590946 • Letter: I
Question
I only need help with the bolded questions.
If the student measured the initial temperature of the solution as 18.2 °C, what would the final temperature be?
Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) H = -306.9 kJ/mol
A student dissolves 0.95 g of Mg in excess HCl. Solve for the heat of reaction when 0.95 g of Mg reacts with excess HCl?
Would this process be exo or endothermic? exothermic
********Therefore, the q = negative
Based on your answer to b, and what you observed in the lab, would you expect the temperature of the solution (surroundings) to increase or decrease? It will increase
Based on your answer to a-c, how much heat is absorbed by the surroundings? 12kJ
1) Using your answer to e, if the solution had a mass of 175.32 g, what temperature change would the student measure for the solution?
2)If the student measured the initial temperature of the solution as 18.2 °C, what would the final temperature be?
Explanation / Answer
moles of Mg = 0.95 / 24 = 0.0396
H = - Q / n
-306.9 kJ/mol = - Q / 0.0396
Q = 12.2 kJ
heat = 12.2 kJ
1) Q = m Cp dT
12.2 x 10^3 = 175.32 x 4.184 x dT
dT = 16.6 oC
dT = T2 - T1
16.6 = T2 - 18.2
T2 = 34.8 oC
final temperature = 34.8 oC