Stoichiometric Relationships
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What is a compound?
More than two elements chemically combined
Homogenous and Heterogeneous mixture
Homogenous mixtures have all substances in one state where Hetero. have substances in different states
Relative atomic mass
Ar is the mean mass of all the isotopes of an element
Relative formula mass
The term used to define the mass of ionic compounds
Relative molecular mass
The sum of elements Ar in a molecule
Mole
The amount of atoms in 12.00g of carbon-12 [6.02 x 10^23]
Properties of a chemical reaction
-New substances are formed -Bonds in the reactants are broken and bonds in the products are formed resulting in an energy change between the reacting system and surroundings -There is a fixed relationship between the number of particles of reactants resulting in no overall change in mass. (The stoichiometry is maintained)
Formula for density and units
mass/volume (g/cm3, kg/m3)
How does pressure change with increasing volume at a constant temp.
Inversely proportional
How does pressure change with an increase of temperature with a constant volume?
Directly proportional
Ideal gas equation and standard units
PV = nRT P= pressure in Pa T= temp in K V= volume in m3 n= no. of moles R= gas constant 8.314 J / (Kelvin x mol)
How does volume change with an increase in temp. at constant pressure?
Directly proportional (linear graph)
Why are the gas laws not fully true and when are they most true
Real gases have some intermolecular forces between particles and the particles take up space. At high temp, low pressures most gases obey the gas laws, making it an ideal gas.
Volume of one mole of a gas at 273K 100000Pa
22.7dm3
Formula for atom Economy
(total mass of desired products / total mass of all products) x 100%
Formula to convert pressure, temp and volume under one set of conditions to another when the mass of a gas is constant (nR is constant)
(P1V1)/T1 = (P2V2)/T2
Boyles law
When temp is constant p1v1 = p2v2
How does pressure change with increasing volume? What would the graph look like?
Pressure decreases with increasing volume, producing an exponential decay graph. If pressure is plotted against 1/V then the graph is linear
Units for Gas Constant R
J / (K x mol)
In what conditions does one mole of a gas occupy 22.7dm3?
273K and 1.0 x 10^5 Pa