Chemical Reactions and Gases in Chemistry - IS

Question 1

How can you tell that a chemical reaction has taken place?

Answer 1

1) a colour change
2) An energy change ( sound, heat, light)
3) A solid is formed ( precipitate)

A NEW SUBSTANCE is always produced.

Question 2

What is a reactant in a chemical reaction?

Answer 2

The chemicals present at the start of the chemical
reaction.

Question 3

What is a product in a chemical reaction?

Answer 3

The new chemicals, which are produced in the
reaction.

Question 4

What is the test for Oxygen?

Answer 4

The test for oxygen is that oxygen will relight a glowing splint.

Question 5

What is the test for Hydrogen?

Answer 5

The test for Hydrogen is that Hydrogen gas burns with a pop.

Question 6

What is test for Carbon Dioxide?

Answer 6

The test for carbon dioxide is that carbon dioxide turns lime water cloudy

Question 7

How do you calculate the % of oxygen in the air?

Answer 7

[ Height water rose (in experiment) ÷ height of cylinder ] x 100 = % of Oxygen in air

Question 8

What is the percent of Oxygen in the air?

Answer 8

20.95%

Question 9

What is the percent of Nitrogen in the air?

Answer 9

78.09%

Question 10

What is the percent of other gases in the air?

Answer 10

0.96%

Question 11

What are the differences between breathed air and breathed out air?

Answer 11

There is less Oxygen than CO2 in breathed out air than in breathed in air

Question 12

How do you collect gases?

Answer 12

Water displacement. Cylinder is placed in a water trough and is filled with water. The cylinder is then flipped upside down, still filled with water. A stopper with a delivery tube in it is placed in a test tube with the reactants in it. The delivery tube is slipped under the bottom half of the cylinder which is in the water.
Gas bubbles will start to appear and the water level will decrease. Downward displacement.

Question 13

What are the properties of Oxygen?

Answer 13

Oxygen has a higher density than air.
Is essential for combustion but is not flammable
Oxygen is highly reactive

Question 14

What are the properties of Hydrogen?

Answer 14

Hydrogen is less dense than air.
Hydrogen is highly flammable
Hydrogen is highly reactive

Question 15

What are the properties of Helium?

Answer 15

Helium is less dense than air.
Helium is inflammable.
Helium is inert (unreactive)

Question 16

What are the properties of Carbon Dioxide?

Answer 16

CO2 is more dense than air.
CO2 is inflammable
CO2 is stable but reacts with some things

Question 17

Why should experiments be repeated?

Answer 17

To make sure that the result was reliable and is a repeated occurrence rather than a random one.

Question 18

What makes a fair test?

Answer 18

One variable is changed.
Controlled variables are correctly implemented.
The experiment could be repeated with the exact same results.

Question 19

How do you calculate averages?

Answer 19

Add all numbers together and then divide by the amount of numbers there.