General Chemistry Answers

This diagram shows two closed, insulated compartments, where no energy can escape. Both compartments contain water of equal volume but varying temperatures of 50°C and 25°C respectively.

If the temperature of the water measuring 50°C decreased by 5°C, the temperature of the water measuring 25°C would

A. remain the same.

B. also decrease by approximately 5°C.

C. increase by approximately 5°C.

D. none of the above

Part A

50 grams of ice-cold water (0 °C) is heated to boiling (100 °C). The specific heat capacity of water is 4.18 J /g°C. How much energy did the water absorb?

Part B

Over the next hour, the water gradually cools to 25 °C. How much energy did the water lose?

Part C

What was the temperature of the room that the water was in?

 A 25 g piece of an unknown metal absorbs 2,000 J of heat and gets 380 °C hotter. Calculate the specific heat capacity and identify the metal using Table 1.

A. Aluminum 0.902

B. Chromium 0.461

C. Lead 0.128

D. Tin 0.213

An element x has atomic number of 29has two isotopes y And Z 34 and 38 respectively.. calculate the mass number for each isotopes and the nuclear symbol.. calculate the percentage abundance

An ideal solution contains 92. 1 g of glycerin, C3H5(OH)3, and 184.4 g of ethanol, C2H5OH, at 40 oC. The vapor pressure of pure ethanol is 0.178 atm at 40 oC. What is the molality of the solution? What is the vapor pressure of a solution?

You have a gas confined to a cylinder with a movable piston. What would happen to the gas pressure inside the

cylinder if you do the following? (a) Decrease the volume to one-fourth the original volume while holding the

temperature constant

Calcium chloride is a compound frequently found in first

-

aid packs. It

gives off heat when

dissolved in water. The following reaction takes place.

a.

What is

Δ

H

when one mole of calcium chloride precipitates from

solution?

b.

What is

Δ

H

when 10.00 g of calcium chloride precipitate?

Salicylic acid, C

7

H

6

O

3

, is one of the starting materials in the manufacture

of aspirin. When 1.00

g of salicylic acid burns in a bomb calorimeter,

the temperature of the bomb and water goes

from 23.11

o

C to 28.91

o

C. The

calorimeter and water absorb 21.9 kJ of heat. How much he

at is

given off

when one mole of salicylic acid burns?

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?

The specific heat of aluminum is 0.902

J/g

·

o

C

. How much heat is absorbed

by an aluminum

pie tin with a mass of 473 g to raise its temperature

from room temperature (23.00

o

C

) to

oven temperature (375

o

F)?