LC CHEMSITRY: STOCHIOMETRY + VOLUMETRICS, PUR CALCULATIONS

What is Avogadro's constant value?

6.02×10²³

What are the particles in an element called?

atoms

What are the particles in a compound called?

molecules

What is the SI unit for the amount of substance?

mole (mol)

What does one mole contain?

exactly Avogadro's number of particles

What is Standard Temperature and Pressure (STP)

the conditions used as a reference for gas calculations

How many Kelvins do we add onto Celsius to convert it to Kelvins?

273K

What is the molar volume AT STP?

22.4 liters

What is Molar mass?

the mass of one mole of a substance in grams

What is the molar mass numerically equal too?

Relative molecular mass

Define “Relative Molecular Mass”

The sum of the relative atomic masses of all atoms in a molecule

What Moles to Mass (in gram) formula?

mass= moles x molar mass

What is the Mass (in grams) to Moles formula?

Moles = Mass /molar mass

What is the Particles from Moles formula?

number of particles = moles x avogardo’s constant

What is the Moles from Volume of Gas formula?

moles = volume in litres/22.4 L

What is the moles to number of atoms formula?

number of atoms= moles x Na x n

• where Na = Avogadro’s number

• where n= number atoms per molecule

What is the molecules to number of atoms formula?

number of atoms= Number of molecules x n

• where n= number of atoms per molecule

What is an Empirical Formula?

the simplest ratio of atoms in a compound. It shows the relative number of atoms of each element

What is an Molecular Formula?

This shows the actual number of atoms of each element in a molecule.

How to do you calculate the percentage composition by mass?

1. convert the percentage to grams e.g. x% is x grams

2. divide the value by the elements relative atomic mass

3. find the ratio by dividing every number by the smallest substance e.g. out of C H O , of is the smallest so we divide everything by O for simpler

4. adjust ratio by rounding to nearest whole number if needed

5. assign the relevant elements for the empirical formula

How do you calculate the masses of reactants and products?

1. find the mass of each element in the compound.

2. convert these masses to moles.

3. use the mole ratio to find the empirical formula

How do you calculate Molecular Formulas from Empirical Formulas?

1. Calculate the molar mass of the empirical formula.

2. Divide the given molecular mass by the empirical formula mass.

   1. Multiply the subscripts in the empirical formula by this value to get the molecular formula e.g

      6(CH₂O)

What is the percentage of an element formula?

Percenage of element= mass of element in 1 moles/molar mass of compound x 100/1

What is a Structural Formula?

shows how atoms are arranged and bonded in a molecule

How do you calculate ppm?

mass of solute (mg)/ volume of solution (L)

What is the Titration Formula?

M1 x V1/n1 = M2xV2/n2

• M₁​: Molarity of solution 1

• V₁: Volume of solution 1

• n₁: Number of moles in the balanced equation for solution 1

• M₂​: Molarity of solution 2

• V₂: Volume of solution 2

• n₂: Number of moles in the balanced equation for solution 2

What is the formula for Molarity?

Molarity= Moles of Solute/ Volume of solution (L)

What is the Unit for molarity?

mol/L

What is the unit for grams (concentration) per litre?

g/L

What is the formula for calculateing the mass of solute in grams per litre of a solution?

Concentration (g/L) = Mass of solute (g)/Volume of solution (L)

What is %(w/v)?

grams of solute per 100ml of solution

What is (v/v)%?

volume of solute per 100ml of solution

What is (w/w)%?

grams of solute per 100g of solution

What is the formula of get the molarity from grams per litre?

Molarity = concentration (g/L)/ molar mass (g/mol)

How do you calculate the moles of a solute using molarity and volume?

Moles of solute=molarity x volume (L)

How do you calculate concentration %(w/v)?

concentration= mass of solute (g)/volume of solution (mL) x 100/1

• where (mL) is a millilitre

How do you calculate concentration %(v/v)?

concentration=volume of solute (mL)/volume of solution x 100/1

What is the Dilution formula and its theory’?

• C₁V₁=C₂V₂

• where C₁ and C₂ are the initial and final

• where V₁ and V₂ are the initial and final

• the number of moles of solute remains the same before and after dilution.