Answer to Question #266386 in General Chemistry for papi

Question

Magnesium sulfate is often used in first

-

aid hot packs, giving off heat when

dissolved in water.

A

coffee

-

cup calorimeter at 25

o

C

contains 15.0 mL of water at

25

o

C

. A 2.00

-

g sample of MgSO

4

is dissolved in the water and 1.51 kJ of heat are

evolved. (You can make the following

assumptions about the solution: volume =

15.0 mL, density = 1.00 g/mL, specif

ic heat = 4.18

J/g

·

o

C

.)

a.

Write a balanced equation for the solution process.

b.

Is the process exothermic?

c.

What is

q

H

2

O

?

d.

What is the final temperature of the solution?

e.

What are the initial and final temperatures in

o

F?

Answer 1

ΔHsolution = MCΔT

M = 15mL×1.00g/mL =15g

C = 4.18 J/g-degree Celsius

ΔT= Change in temperature = final temperature -initial temperature

ΔHsolution =1.51kJ=1.51×1000=1510J

Given, ΔHsolution = MCΔT

1510J = 15g×4.18 J/g-℃×ΔT

1510J = 62.7J/℃×ΔT

ΔT= 1510J÷62.7J/℃

= 24.08℃

ΔT= Change in temperature = final temperature -initial temperature

24.08℃ = final temperature-25 ℃

final temperature=24.08℃+25 ℃

=49.08℃

=49℃