Formulas and Equations Flashcards
What is the empirical formula?
The smallest whole number ration between atoms of each element in a compound
What is the molecular formula?
The actual number of atoms of each type of element in a molecule
What are the 3 steps, if you know the empirical formula and the molecular mass of a compound, to calculate it’s molecular formula?
1- Find the empirical mass (mass of the empirical formula)
2-Divide the molecular mass by the empirical mass
3-Multiply the empirical formula by that number
What are the 4 steps for calculating the empirical formula from experimental data?
1-Use the equation, moles = mass / Mr, to work out how many moles of each product you have
2-Use the moles of each product to work out how many moles of each atom you started with
3-Write down the ratio of moles present at the start and then divide by the smallest to get the simplest whole number ratio
4-This is the empirical formula
What are the 3 steps for calculating the empirical formula from percentage compositions?
1-Assume you’ve got 100g of the compound, so you can turn the percentages into masses, then work out the moles of each element
2-Divide each number of moles by the smallest number of moles you found to get the smallest whole number ratio
3-Apply the numbers from the ratio to the formula
What 2 things do you need to know to be able to calculate the molecular formula?
Empirical formula and the molar mass
How do you find the factor that you need to multiply the empirical formula by to get the molecular formula?
Divide the molar mass by the empirical formula
What are the 4 state symbols?
s = solid l = liquid g = gas aq = aqueous (solution in water)
How are ions formed?
Formed when electrons are transferred from one atom to another
What charge of ion does Zinc form?
2+
What charge of ion does Silver form?
1+
What charge of ion does Iron (II) form?
2+
What charge of ion does Iron (III) form?
3+
What charge of ion does Copper (I) form?
1+
What charge of ion does Copper (II) form?
2+
