Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
27 Cards in this Set
- Front
- Back
|
What is valency? |
A number assigned to each element that indicates the number of electrons that it has lost/gained in order to become stable. |
|
|
What is the equation for atom economy? |
Atom Economy = sum of Mr of desired products / sum of Mr of all products x 100 |
|
|
Define mole |
A mole is the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of carbon-12. |
|
|
What is the Avagadro Constant? |
The number of atoms per mole of the carbon-12 isotope. 6.02e23 |
|
|
What is relative molecular mass, Mr? |
The average mass of a molecule compared to carbon-12. This is used for simple molecular (covalent) molecules. |
|
|
What is relative formula mass? |
The average mass of the formula compared to carbon-12. This is used for giant structures. Practically the same as Mr. |
|
|
Define Molar Mass |
The mass per mole of a substance (g/mol). |
|
|
What is the equation for calculating moles? |
moles (n) = mass (m) / molar mass (M) |
|
|
What is the equation for % yield? |
% yield = actual mass / theoretical mass x 100 |
|
|
What are the conditions for RTP? |
297K, 101kPa
|
|
|
At RTP, what volume does 1 mole of gas occupy? |
24dm^3 |
|
|
What is the concentration equation? |
concentration (c) = moles (n) / volume (v) |
|
|
When do we use the ideal gas equation? |
When the pressure or temperature is not at RTP. |
|
|
What is the ideal gas equation? State what each of the symbols mean.. |
pV = nRT p -> pressure in pascals V -> volume of gas in m^3 n -> number of moles R -> The gas constant T -> temperature in kelvins. |
|
|
What are ideal gas particles assumed to be? |
In rapid random motion Elastic collisions (don't kinetic energy) Negligible size No intermolecular forces |
|
|
State the steps of the an experiment to find the relative molecular mass, using the ideal gas equation. |
This only works if the unknown liquid is liquid at RTP and has a boiling point below 373K (100 degrees celsius ), as otherwise it won't vaporise. 1. Add a sample of the volatile liquid to a small syringe via a needle. Weigh the small syringe. 2. Inject the sample into the gas syringe through the self-sealing rubber cap, Reweigh the small syringe to find the mass of the volatile liquid added to the gas syringe. 3. Place the gas syringe in a boiling water bath at 373K. The liquid vaporises, producing a gas. The volume is recorded. |
|
|
Define concentration |
The concentration of a solution is the amount of solute, in mol, dissolved in 1 dm^3 (1000cm^3) of solution. The units are moldm^-3 or gdm^-3 |
|
|
What are titrations used for? |
To find find the concentration of an acid or alkali (base). |
|
|
What is the formula for ethanoic acid? |
CH3COOH |
|
|
What are the steps for calculating the formulas of metal oxides? |
1. subtract the mass of the metal from the mass of the solid oxide formed to find the mass of oxygen. 2. calculate the number of moles of each element. 3. divide the number of moles of each element by the smallest value. |
|
|
What is stoichiometry? |
Where you use a balanced chemical equation to calculate amounts of reactants and products. |
|
|
Define empirical formula |
Empirical formula is the simplest whole number ratio of atoms of each element in a compound. |
|
|
Define molecular formula. |
Molecular formula is the actual number of atoms of each element in a compound. |
|
|
What are the steps for determining the empirical / molecular formula? |
1. find moles of each element (from mass or % of element). 2. divide by the smallest number 3. use the whole number ratio to deduce empirical formula. 4. use molar mass/Mr to calculate molecular formula |
|
|
What is water of crystallisation? |
water molecules which make up the part of the crystal structure of a compound, that can be removed by heating. |
|
|
What is mean't by anhydrous? |
It's the compound which remains when the water is removed from a hydrated salt. |
|
|
What is mean't by hydrated? |
It's a complex molecule which has water molecules incorporated. |
