Quantitative Chemistry Flashcards
1
Q
How to calculate the % mass of an element in a compound ?
A
Relative atomic mass X no. of atoms of the element
÷
Relative formula mass of the compound
2
Q
What is Avogadro’s constant?
A
1 mole = 6.02 X 10²³
3
Q
Formula for moles ? (Mass, rfm)
A
Moles = mass / rfm
4
Q
Why might mass appear to decrease in a reaction ?
A
One of the products is a gas and it may escape.
5
Q
Why might the mass appear to increase in a reaction ?
A
One of the reactants is a gas.
6
Q
How to balance equations using reacting masses ? 1-4
A
- Find the number of moles of each substance.
- Divide the number of moles of each by the smallest number of moles.
- If any of the numbers aren’t whole, make them whole.
- Write a balanced symbol equation putting these numbers in front of the chemical formulas.
7
Q
One mole of any gas occupies how many dm³ ?
A
24 dm³
8
Q
Calculation for the volume of gas ? ( Mass of gas, Mr of gas)
A
Volume(dm³) = mass/Mr X 24
