Question

#1: Which of the following is an endothermic reaction?

A. an explosion

B. condensation of steam

C. freezing water

D. thawing ice

**my answer; D. thawing ice

is that right? :) @aaronq :)

Answer 1

#2: A copper block (90°C) is placed in contact with a lead block (20°C), which is already in contact with an iron block (70°C). Which of the following will happen?

A. Heat will flow from the copper to the lead to the iron until the temperatures are equal.

B. Heat will flow from the iron to the lead to the copper until the temperatures are equal.

C. Heat will flow from the copper to the lead and from the iron to the lead until the temperatures are equal.

D. Heat will flow from the lead to the copper and to the iron until the temperatures are equal.

***my answer: C

is that right? :)

Answer 2

hmm changing states of matter isn't a reaction..

Answer 3

#3: Using the attached table, when two substances with the same mass are heated by the same amount, which pair would heat up at about the same rate?

A. iron and aluminum

B. aluminum and gold

C. gold and copper

D. copper and iron

**im not too sure on this one :(

what do u think?

Answer 4

wait so what does that mean then? and are u referring to #1? :/

Answer 5

#4: In the coffee-cup calorimeter you used in the laboratory, which of the following statements is true?

A. The water is the system and the ice is the variable.

B. The foam cups are not part of the system.

C. The water is part of the system.

D. The foam cups are the only part of the system.

***my answer: C

is that right?:)

Answer 6

yeah, i mean if it said "process" then sure, thawing ice is an endothermic process, but not a reaction.

Answer 7

#5: Hydrogen gas explodes when burned with oxygen gas. Where does this energy come from?

A. kinetic energy of the hydrogen molecules

B. kinetic energy of the oxygen molecules

C. work done on both oxygen and hydrogen molecules

D. chemical bonds between hydrogen atoms and between oxygen atoms

***my answer: D

is that right?:)

Answer 8

yeah it says reaction... :/ so what would #1 be then? :/

Answer 9

2 is good.

for 3, you're looking for the substances with the specific heat capacities closest to each other

Answer 10

#1 i think they meant process, so you're right.

Answer 11

sooo would #3 be D. copper and iron then?

and yay for #2!

Answer 12

okay! :)

Answer 13

5 is good !

Answer 14

awesome! :) what about 3 and 4 then ? :)

Answer 15

4 is good

Answer 16

for 3, look at what i wrote earlier :P

Answer 17

awesome! :) and okay... so for 3, I'm not too sure then.. i thought it was copper and iron? cuz copper is 0.39 and iron is 0.46 :/ idk haha :/

Answer 18

yep!

Answer 19

okay! awesome! thanks :)

Answer 20

no problem!