Test of 3/13/23

Question 1

List all of the signs of chemical changes (there are 7 of them )

Answer 1

1. new substance was formed
2. bubbling or fizzing (gas ) produced
3. light or heat produced
4. change in energy
5. change in color or odor
6. precipitates formed
7. smoke produced

Question 2

are when two atoms bonded together

Answer 2

Diatomic molecules

Question 3

What is needed to break or form bonds

Answer 3

energy

Question 4

speeds up a reaction by lowering the activation energy of a reaction

Answer 4

catalyst

Question 5

Go to this website for the practice problems !
https://www.mayfieldschools.org/Downloads/Counting%20Atoms%20_2%20and%20KEY.pdf

Answer 5

Go to this website (pdf page 2) for the answers!
https://www.mayfieldschools.org/Downloads/Counting%20Atoms%20_2%20and%20KEY.pdf

Question 6

If no subscript is written in the chemical formula…

Answer 6

then there is only 1 atom of that chemical

Question 7

What law states that the equations must be balanced

Answer 7

The law of Conservation of Mass

Question 8

The law of Conservation of mass says that

Answer 8

equations must be balanced and mass can never be created nor destroyed during ordinary chemical or physical changes.

Question 9

need to know how to balance a chemical equation

Answer 9

Here is practice http://alexanguiano.com/yahoo_site_admin/assets/docs/balancews_key24115555.27174753.pdf

Question 10

a reaction in which two or more substances combine to form a compound

Answer 10

A synthesis reaction

Question 11

a reaction in which a compound breaks down to form two or more simpler substances

Answer 11

A decomposition reaction

Question 12

a reaction in which an element takes the place of another element that is part of a compound

Answer 12

a single displacement reaction

Question 13

a reaction in which ions in two compounds exchange places

Answer 13

a double displacement reaction

Question 14

ways to increase the rate of a reaction is (4)

Answer 14

1. raise the temperature
2. increase the concentration
3. increase surface area by grinding or breaking the substance
4. add a catalyst

Question 15

if energy is written on the reactant side of the equation it is….

Answer 15

An endothermic reaction

Question 16

if energy is written on the product side of the equation it is….

Answer 16

an exothermic reaction

Question 17

Identify the
Coefficient,
Subscript,
product,
reactant,
yield sign
based on the enlarged picture : https://www.google.com/search?q=chemical%20equation%20examples&tbm=isch&rlz=1CAXXPU_enUS1021&hl=en-US&sa=X&ved=0CB8QtI8BKABqFwoTCOC4x_Hb0v0CFQAAAAAdAAAAABAN&biw=1300&bih=629&safe=active&ssui=on#imgrc=QRNz62NhdeQlfM

Answer 17

Coefficient- 2
Subscript(s)- 2,2,3
Product- right side
Reactants- left side
yield sign (as the reaction is taking place)- the arrow in the middle

Question 18

a force that holds two atoms together

Answer 18

a chemical bond

Question 19

when molecules bump into each other with enough energy what happens

Answer 19

chemical bonds break

Question 20

After chemical bonds break

Answer 20

atoms rearrange themselves to form new substances with properties different than the original substances. (chemical reaction)

Question 21

when energy is taken in or absorbed

Answer 21

endothermic

Question 22

when energy is released or taken away

Answer 22

exothermic

Question 23

Grab your study guide and look at figure 4 on the back of it and tell the diffrence between the two

Answer 23

try to not look at the answers while doing it.