C3a - Quantative Chemistry Flashcards
1
Q
What is the conservation of mass? (3)
A
The atoms have been re-arranged, not lost or gained.
In reactions there are the same number of atoms before and after.
Atoms cannot be created or destroyed.
2
Q
What is an example of conservation of mass?
A
When a Gad if produced and allowed to escape, the difference is the mass of gas.
3
Q
Why do equations have to be balanced?
A
Due to Conservation of Mass
4
Q
What is a level of uncertainty?
A
Half the range of measured values
5
Q
What is an example of percentage by mass? H in NH3?
A
- Find the % of H in NH3
(1x3/17) x 100 = 17.3%
6
Q
What is the equation for working out concentration?
A
Concentration = mass/ volume
(g/dm3)
7
Q
How to change from dm3 to cm3?
A
1dm3 = 1000cm3
Cm - dm /1000
8
Q
What is concentration?
A
The mass of a solute (solid) dissolved in a solvent (liquid).
9
Q
A
