Answer:
mass (g) needed = 710.2 grams Na₂SO₄(s)
Explanation:
Needed is 2.5 Liters of 2.0M Na₂SO₄; formula wt Na₂SO₄ = 142.04g/mol.
mass (grams) of Na₂SO₄(s) = Molarity needed x Volume needed in Liters x Formula Wt of solute
mass (grams) of Na₂SO₄(s) = (2.5L)(2.0M)(142.04g/mol) = 710.2 grams Na₂SO₄(s)
Mixing: Transfer 710.4 grams Na₂SO₄ into mixing vessel and add water-solvent up to but not to exceed 2.5 Liters total volume. Mix until dissolved.
Gives 2.5 Liters of 2.0M Na₂SO₄(aq) solution.
Is a solid? has strong intermolecular forces?
2H2 + O2 →2H2O
This is a limiting reactant problem in which you need to figure out which reactant is the limiting reactant. You can usually look at the information given and see that hydrogen has the smaller amount of mass used, but it is always good to check that assumption through stoichiometry:
(9.43g H2/2.02g/mol)(2mol H2O/2mol H2)(18.02gH2O/1mol H2O)= 84.1g H2O produced from 9.43g of H2
(12.98g O2/32.00g/mol O2)(2mol H2O/1mol O2)(18.02gH2O/1mol H2O)= 14.6g H2O
So my assumption that hydrogen makes the smaller amount of water is wrong since oxygen (it is the limiting reactant) created the smaller amount of water with 14.6g, so 14.6g is the maximum amount of water that can be formed
An atom contains protons, neutrons and electrons.
Protons have a positive charge (+1).
Neutrons have no charge (0)
Electrons have a negative charge (-1)
The number of protons and electrons is always the same and so the charges add up to make 0. Therefore there is no overall charge on atoms.