Carbon
This allotrope of carbon is used in cutting tools because it is extremely hard.
Diamond
Which subatomic particle is responsible for electric current in electrolysis?
electrons
When the volume of a gas increases at constant temperature, what happens to its pressure?
It decreases- Boyles' law
What is the smallest particle of an element that retains its chemical properties?
Atom
What is one mole equal to in terms of number of particles?
6.02 x 1023 particles
When carbon burns in excess oxygen, this gas is formed.
Carbon (IV) oxide
Why does distilled water conduct electricity poorly?
It has very few ions
Why must temperature be converted to Kelvin when solving gas law calculations?
Because gas laws only work with absolute temperature (Kelvin scale)
Define the anode in electrolysis
What is the molecular mass of CO₂?
C=12, O=16
12+16+16 = 44
Name the white solid formed when carbon (IV) oxide is passed through limewater.
Calcium carbonate
CO2 + Ca(OH)2 --> CaCO3 + H2O
Why does solid sodium chloride not conduct electricity?
Its ions are not free to move
State one condition that must be constant for Charles’ law to apply.
pressure
What type of bond is formed when electrons are shared between atoms?
Covalent bond
Calculate the number of moles in 5.85grams of sodium chloride.
(Molar mass NaCl = 58.5 g/mol)
moles = mass/molar mass
5.85/58.5= 0.1
Explain why carbon (II) oxide can reduce copper (II) oxide when heated.
It removes oxygen from copper (II) oxide (acts as a reducing agent)
In electrolysis of lead (II) bromide (PbBr2), which gas is produced at the cathode?
Bromine gas, Br2
Which gas diffuses faster: hydrogen or oxygen? Explain why.
Hydrogen; it has a lower relative molecular mass.
Why are noble gases generally unreactive?
They have full outer electron shells. No valence electrons
A student dilutes 25 cm³ of a 2.0 mol/dm³ solution to a final volume of 100 cm³.
What is the new concentration?
M1V1=M2V2
M1 = 2M
V1=25cm3
M2 = ?
V2 = 100cm3
2.0×25=M2×100
0.5M
During heating of limestone, a gas is released and a solid residue remains. Name the gas product that is released.
Carbon (IV) oxide
Explain why graphite is used as an electrode in electrolysis.
It conducts electricity, is non reactive and inexpensive
A gas occupies 100 cm³ at 273 K. What will happen to the volume if the temperature increases to 546 K at constant pressure?
It doubles to 200 cm³
V1/T1 = V2/T2
100/273 = V2/546
Balance this equation: Al + O₂ → Al₂O₃
4Al + 3O₂ → 2Al₂O₃
What is the mass of 0.5 moles of CaCO₃?
(Ca = 40, C = 12, O = 16)
Molar mass: 40+12+(16×3)=100
Mass/Molar Mass = Number of moles
x/100g = 0.5moles
x=50g