Topic 3 Flashcards
What are the four states?
(g) gas, (l) liquid, (aq) aqueous, (s) solid
What is the arrow used for in chemical equations
To show reactants turning into products
What substances are always gases?
O2, N2, H2, Cl2 and any noble gases are always gases
What substances are always solids?
Metals
What substance is nearly always a liquid?
H2O (water)
What substances are aqueous most of the time?
Ionic compounds
What is the law of conservation of mass?
During chemical change there is no loss or gain of atoms. The mass of the products in a chemical reaction must equal the mass of the reactants
What 7 elements are diatomic molecules?
Oxygen, hydrogen, chlorine, nitrogen, fluorine, iodine and bromine
How to write and balance chemical equations?
- Write the correct formula for the reactants and products, including state symbols
- Count the number of each type of atom on each side of the equation
- If needed add coefficients in front of unbalanced substances until it’s balanced. Hint: balance oxygen and hydrogen last
What are ionic half equations for?
Used to show if electrons have been gained or lost (always add the electrons can’t subtract it and add them on the most positive side)
What is the relative atomic mass?
The average mass of the isotopes of an element compares to 1/12th the mass of an atom of carbon-12
How do you find relative atomic mass with abundance of isotopes?
atomic mass= (fractional abundance of isotope 1 x mass of isotope 1) + (fractional abundance of isotope 2 x mass of isotope 2)
What is the relative molecular mass?
The sum of all the relative atomic masses of each element in a compound. It has a unit of g mol-1
What’s the formula for moles using mass and molecular mass.
n=m/Mr
moles= mass/molecular mass
Why is volume used to find the number of moles of a gas?
Because the mass of a gas is so small. Equal amounts in moles of gases occupy the same volume under the same conditions