Question

Given that the specific heat of water is 4.18 kJ/(kg·°C), how much heat does it take to raise the temperature of 3.5 kg of water from 25°C to 55°C?

Answer 1

q = mc * deltaT

where m = mass
c = specific heat
deltaT = change in Temperature

Answer 2

3.5*4.18*20

Answer 3

292.6

Answer 4

check the change in temperature again, 55 - 25 is 30 not 20

Answer 5

3.5*4.18*30 = ?

Answer 6

438.9

Answer 7

good

does your teacher care about significant figures (sig figs) or nah? b/c it would be 440 kJ if we round to significant digits

Answer 8

I can put both :p

Answer 9

sure

Answer 10

What is the mathematical equation for calculating the heat needed to change the temperature of a substance? Identify each variable and its units.

Answer 11

q = mc * deltaT, explanations are at the top

Answer 12

q = mc * deltaT

where m = mass
c = specific heat
deltaT = change in Temperature

Answer 13

yup, any thoughts on units?

Answer 14

mass would be SI

Answer 15

[ok, so they gave you kg in the problem, but usually we would use grams for mass]

so T is celcius
m is grams
specific heat = J/(g·°C)

Answer 16

oh, yeah, q is heat which is joules

Answer 17

Sooo,
q = mc * deltaT

where m = mass
c = specific heat
deltaT = change in Temperature

T is celcius
m is grams
specific heat = J/(g·°C)

Answer 18

yes

Answer 19

Define specific heat capacity and latent heat of fusion.

Specific heat capacity is the heat that is required to raise the temperature of the unit mass of a given substance. Latent heat of fusion is energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process that is specified in some way.

Answer 20

not bad but for latent heat of fusion it should be mentioned that this is the heat required to convert a substance from its solid to its liquid form (fusion)

Answer 21

Specific heat capacity is the heat that is required to raise the temperature of the unit mass of a given substance. Latent heat of fusion is energy that is released or absorbed during a constant-temperature process that is pinpointed in some way. Also, the heat in a latent heat of fusion is the heat required to convert a substance from its solid to its liquid form

Answer 22

good

Answer 23

How do particle motion and temperature change as a material absorbs heat?

Answer 24

Particle motion and temperature both increase as a material absorbs heat.

Answer 25

good

Answer 26

A physics student is sitting at the beach. She feels the warm Sun shining on her back, the warm sand under her feet, and a cool breeze blowing in from the water. Identify each type of heat transfer she is experiencing.

Answer 27

warm Sun shining on her back- radiation
warm sand under her feet-
cool breeze blowing in from the water-

Answer 28

well there are only two other types of heat transfer, conduction and convection, which one would be conduction and which one would be convection

Answer 29

warm Sun shining on her back- radiation
warm sand under her feet-convection
cool breeze blowing in from the water-conduction

Answer 30

other way around, conduction requires contact so that would be feet touching the sand

Answer 31

a. Match the term to its correct description. (1 point)

A. Convection
B. Radiation
C. Thermal conductor
D. Thermal insulator
E. Conduction


_____ A substance that transfers heat poorly

_____ Heat transfer through direct contact of particles

_____ Heat transfer through motion of a fluid

_____ Heat transfer through electromagnetic waves

_____ A substance that transfers heat well

Answer 32

Heat transfer through motion of a fluid
is convection

Answer 33

good

Answer 34

Heat transfer through electromagnetic waves is radiation

Answer 35

yup

Answer 36

A substance that transfers heat well is conduction

Answer 37

that's not quite right, you're thinking of conductor

Answer 38

__D___ A substance that transfers heat poorly

__E___ Heat transfer through direct contact of particles

__A___ Heat transfer through motion of a fluid

__B___ Heat transfer through electromagnetic waves

__C___ A substance that transfers heat well

Answer 39

awesome

Answer 40

work = P*deltaV, where would work be 0?

Answer 41

the bottom

Answer 42

not quite, the volume is decreasing there so work would be nonzero

where is the volume constant?

Answer 43

Would it be this

Answer 44

good, so the volume is constant on the left and right sides on the shape

what about "isobaric process"? where is the pressure constant?

Answer 45

Um on the left

Answer 46

hm, not quite, if you compare points 1 and 4 see how the pressure is different? that means the left side is a process with non-constant pressure

where on the graph is the pressure the same across both points?

Answer 47

top and bottom

Answer 48

awesome, so that would be your isobaric processes

so, for work done on system, that means the volume must be going down, where would that be?

Answer 49

left side

Answer 50

notice how the volume is the same on the left side between points 1 and 4

Answer 51

volume is on the x-axis, which side on the graph shows a decreasing x-value?

Answer 52

the other side because points 1 and 4 show it going up

Answer 53

that's pressure not volume

Answer 54

what about work done by the system? that would be increasing volume, so which side?

Answer 55

opposite of the decreasing

Answer 56

good, so the top side

and that's it

Answer 57

Something like this right

Answer 58

good, it's a bit incomplete atm, ex. no work done needs to be on the right side to

also, for "work done" you need to specify whether the system is doing work or having work done on it

Answer 59

*on the right side too

Answer 60

the top side is expansion, thats work done (by) system not on system

work done on system = bottom side

Answer 61

good

as a minor issue the instructions say to label it as "W = 0J" not "no work done" so just change those labels and you'll be set

Answer 62

good, that's it

Answer 63

you're given e = W/Qin, work and heat-in are given in the problem, find e

Answer 64

e = W/Qin
e=300/600
e=0.5

Answer 65

good, efficiency is often a percentage so we could report this as 50%

Answer 66

A is ice

Answer 67

good

what about KE? does it change?

Answer 68

b is freezing/melting ice or water

Answer 69

no

Answer 70

for A) yes the KE does change (since heat is being put in + temp is changing)

B) no since temp isn't changing

Answer 71

A is ice
Yes kinetic or potential energy does change

B is freezing/melting ice or water
No kinetic or potential energy doesn't change because the temperature is not changing

C is water
Yes kinetic or potential energy does change

D is boiling/condensing water or gas
Yes kinetic or potential energy does change

Answer 72

E is gas
No kinetic or potential energy does not change

Answer 73

check D and E again for KE changes

Answer 74

D is boiling/condensing water or gas
No kinetic or potential energy does not change

E is gas
Yes kinetic or potential energy does change

Answer 75

good, what about the last column, for each letter which heat capacity would you use?

Answer 76

hint - for the phase changes it would be "latent heat of ______" whatever phase change it is

and for the parts where the temperature changes it would be "specific heat capacity of ____" whatever phase its in right now

Answer 77

A. Specific heat capacity of solid
B. Latent heat of
C.Specific heat capacity of liquid
D. Latent heat of
E.Specific heat capacity of gas

Answer 78

for water, what would the names for its solid/liquid/ and gas forms be?

Answer 79

ice water and um

Answer 80

water vapor

Answer 81

for the phase change names, what's the name for a substance turning from solid to liquid, and then from liquid to vapor?

Answer 82

melting and evaporation

Answer 83

good but in chem/physics we usually call these fusion/vaporization

so latent heat of melting/ latent heat of vaporization for B + D

Answer 84

A. Specific heat capacity of solid
B. Latent heat of melting
C.Specific heat capacity of liquid
D. Latent heat of vaporization
E.Specific heat capacity of gas

Answer 85

replace solid/liquid/gas with the names of their forms for water

replace melting with its scientific name, fusion

Answer 86

A. Specific heat capacity of solid
B. Latent heat of fusion
C.Specific heat capacity of liquid
D. Latent heat of vaporization
E.Specific heat capacity of gas

Answer 87

\(\color{#0cbb34}{\text{Originally Posted by}}\) @Vocaloid
*** replace solid/liquid/gas with the names of their forms for water ***

replace melting with its scientific name, fusion
\(\color{#0cbb34}{\text{End of Quote}}\)

Answer 88

A. Specific heat capacity of ice
B. Latent heat of fusion
C.Specific heat capacity of water
D. Latent heat of water vapor
E.Specific heat capacity of gas

Answer 89

D is latent heat of vaporization
E is specific heat capacity of water vapor

Answer 90

A. Specific heat capacity of ice
B. Latent heat of fusion
C.Specific heat capacity of water
D. Latent heat of vaporization
E.Specific heat capacity of water vapor

Answer 91

good