Chemistry Flashcards
State the percentage of the gases- nitrogen, oxygen, argon and other gases, in air
78%
21%
0.9%
0.1%
State the reactions taking place in a catalytic converter.
2CO + O2 –> 2C02
2NO + 2CO –> N2 + O2
2NO –> N2 + 02
What are the 3 states of matter?
Solid
Liquid
Gas
What is a volatile liquid?
A liquid which evaporates easily and has a relatively low boiling point
What does impurity do to a substance?
- Lowers the melting point
- increases the boiling
point
What does the word miscible mean?
The solvents make a solution
How to calculate Rf value in chromatography?
Distance moved by the substance/distance moved by the solvent front
What are isotopes?
Atoms of the same element which have the same proton number but a different nucleon number
What are radioisotopes?
Isotopes which emit a certain type of radiation.
What metals are the most reactive metals that occur?
Alkali metals
What are exothermic and endothermic reactions?
Reactions which give-off energy (exothermic)
Reactions with take-in energy (endothermic)
What is the law of conservation of mass?
The total mass of all products of a chemical reaction is equal to the total mass of all reactants.
Briefly explain the following chemical reactions:
- synthesis
- decomposition
- neutralisation
- precipitation
- displacement
- where two/more reactant form a single product
- where one reactant forms many products
- where an acid and an alkali react to form salt
- where an insoluble solid is formed
- where a more reactive element will displace the less reactive one
What are oxidising and reducing agents?
A substance that will add oxygen to a substance (oxidising)
A substance that will remove oxygen from a substance (reducing)
Fill in the blanks:
____ is the loss of electrons
____ is the gain of electrons
Oxidation
Reduction
What is electrolysis?
The breakdown of an ionic compound, molten or in aqueous solution, by the use of electricity
State whether the following are positive or negative:
Cation
Anion
Cathode
Anode
Positive
Negative
Negative
Positive
What does the following do to a litmus paper:
Acid
Base
Turns it red
Turns it blue
Fill in the blanks:
Non-metals generally form ____ that dissolve in water to form ____ solutions
Metals generally form ____ that dissolves in water to form ____ solutions
Acidic oxides, acidic
Alkaline oxides, basic
What is amphoteric hydroxide?
A hydroxide that reacts with both an acid and an alkali to give salt and water
What is the test for ammonium salts?
They react with alkali solutions to produce ammonia gas.
State the Avogadro constant.
6.02 x 10^23
What is the formula to calculate molar-mass?
Mass/no.of moles
What is the formula to calculate molar-volume?
Volume/no.of moles
What is the molar volume of any gas?
24dm^3
What is the formula to calculate concentration?
Amount of solute/volume of solution
What is the formula to calculate no.of moles in a solution?
(Concentration/1000) x volume of solution in cm^3
Fill in the blanks:
a) Breaking chemical bonds is an __________ process.
b) Making chemical bonds is an __________ process.
a) Endothermic
b) Exothermic
State five factors that affect the rate of a reaction.
Surface area
Concentration
Temperature
Catalyst
Influence of light (only sometimes)
What happens to the temperature of the surroundings in the following:
a) endothermic reaction
b) exothermic reaction
a) decreases; thermal energy is absorbed
b) increases; thermal energy is given-off
What is activation energy?
The minimum quantity of energy, the reactant must possess to undergo a specific reaction
Fill in the blanks:
a) Each reaction has its own different value of __________
b) When particles collide, they must have a combined energy __________ than the __________ energy, or else, they will not react
c) Chemical reactions occur when particles __________ with each other
a) Activation
b) Greater, activation
c) Collide
Give five factors which affect the rate of a reaction.
Surface area (of solid reactants)
Concentration
Temperature
Catalyst
Influence of light (only sometimes)
State the catalysts used in the:
a) Haber process
b) Contact process
a) Iron
b) Vanadium oxide
State what is meant by:
a) Valency
b) Valence electron
a) The combining capacity of an atom (Na- 1)
b) The electrons in the outermost shell of an atom (Na- 1; 1 electron in the
outermost shell)
Fill in the blank:
Zinc displaces copper because zinc is more _________ than copper.
Reactive
