# Formulae, Equations And Amounts Of Substance Flashcards Preview

## Chemistry A level Edexcel > Formulae, Equations And Amounts Of Substance > Flashcards

Flashcards in Formulae, Equations And Amounts Of Substance Deck (27)
1
Q

Define a mole

A

Unit for amount of substance: the amount of chemical species found in 12g of carbon-12

2
Q

A

Number of atoms in exactly 12g of carbon-12.

6.02 x 10^23

3
Q

Define molar mass

A

Mass of 1 mole of the substance in g/mol

4
Q

Define relative molecular mass

A

Average mass of a molecule relative to 1/12 mass of carbon-12 atom

5
Q

Define empirical formula

A

Smallest whole number ratio of atoms of each element in a compound

6
Q

Define molecular formula

A

Actual number of atoms of each element in a molecule

7
Q

Define spectator ion

A

Ions that do not take part in the reaction

8
Q

What is a hydrate?

A

A compound that has waters of crystallisation

9
Q

What is a standard solution?

A

One with an accurately known concentration

10
Q

What is mass concentration?

A

Mass of solute per volume unit of solution - gdm^-3

11
Q

What is molar concentration?

A

Moles of solute per volume of solution - moldm^-3

12
Q

What is a primary standard?

A

A substance used for preparation of a standard solution

13
Q

A

Provided the conditions of temperature and pressure are the same, equal volumes of gas contain the same number of molecules

14
Q

What is molar volume?

A

Volume of 1 mole of gas

15
Q

What is a displacement reaction?

A

A more reactive element reacts to take the place of a less reactive element in a compound

16
Q

What is a precipitation reaction?

A

One that produces an insoluble solid (precipitate)

17
Q

What is an error?

A

A discrepancy between the value obtained in an experiment and the actual value

18
Q

What is precision?

A

Reference to how close each value is to each other obtained in an experiment

19
Q

What is accuracy?

A

Reference to how close obtained values are to the actual value

20
Q

What are concordant results?

A

Results that lie close to each other, usually titrates that lie within 0.20cm^3 (+/- 0.10cm^3)

21
Q

What is a margin of error?

A

The range in which the true values could lie

22
Q

What are random errors?

A

They occur when conditions are varied in an unpredictable manner

23
Q

What are systematic errors?

A

Errors which are constant when you repeat an experiment, usually result of an apparatus used

24
Q

What is the equation for percentage uncertainty?

A

(Actual yield / theoretical yield) x 100 (%)

25
Q

What is atom economy?

A

Measure of the proportion of atoms that become part of the desired product in the balanced chemical equation

26
Q

What is the equation for atom economy?

A

(Mr of desired product / total Mr of all products) x 100 (%)

27
Q

What does each letter of the pv = nRT equation represent?

A
```p = pressure (Pa)
v = volume (m^3)
n = moles (mol)
R = ideal gas constant: 8.314
T = temperature (k)```