Chemical Reactions and Gases in Chemistry Flashcards
How can you tell that a chemical reaction has taken place?
1) a colour change
2) An energy change ( sound, heat, light)
3) A solid is formed ( precipitate)
A NEW SUBSTANCE is always produced.
What is a reactant in a chemical reaction?
The chemicals present at the start of the chemical
reaction.
What is a product in a chemical reaction?
The new chemicals, which are produced in the
reaction.
What is the test for Oxygen?
The test for oxygen is that oxygen will relight a glowing splint.
What is the test for Hydrogen?
The test for Hydrogen is that Hydrogen gas burns with a pop.
What is test for Carbon Dioxide?
The test for carbon dioxide is that carbon dioxide turns lime water cloudy
How do you calculate the % of oxygen in the air?
[ Height water rose (in experiment) ÷ height of cylinder ] x 100 = % of Oxygen in air
What is the percent of Oxygen in the air?
20.95%
What is the percent of Nitrogen in the air?
78.09%
What is the percent of other gases in the air?
0.96%
What are the differences between breathed air and breathed out air?
There is less Oxygen than CO2 in breathed out air than in breathed in air
How do you collect gases?
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.
What are the properties of Oxygen?
Oxygen has a higher density than air.
Is essential for combustion but is not flammable
Oxygen is highly reactive
What are the properties of Hydrogen?
Hydrogen is less dense than air.
Hydrogen is highly flammable
Hydrogen is highly reactive
What are the properties of Helium?
Helium is less dense than air.
Helium is inflammable.
Helium is inert (unreactive)
