quantitative chemisty
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How many different elements are in sulphuric acid, H2SO4
2(H) + S + 4(O) = 3 elements
How many atoms make up one molecule of H2SO4
2(H) + S + 4(O) = 2 + 1 + 4 = 7 atoms
What does Ar mean?
Relative atomic mass
What does Mr mean?
Relative formula mass
Describe how to calculate the relative formula mass (Mr) of a molecule?
Add up mass numbers (top number) of all the atoms in the molecule
What does conservation of mass in a chemical reaction mean?
In a chemical reaction, no atoms are created or destroyed
What does conservation of mass in a chemical reaction mean?
If mass decreases then a product was a gas If mass increases then a reactant was a gas
Describe how would calculate the uncertainty of a set of results
Work out the range (from difference between highest and lowest results) · Divide by two
State the value of the Avogadro constant
6.02 x 1023
What is a mole
One mole of a substance contains Avogadro’s number of particles
State the formula that relates the number of moles of a substance to its mass and Mr?
Mass (g) = number of moles x relative atomic mass
What is a limiting reactant?
A reactant that is used up in a reaction
How do you calculate the mass of a product if you know how much of a limiting reactant you have?
• Write out the balanced equation · Work out the Relative atomic mass of the reactant and the product you want · Convert the relative atomic mass of the limiting reactant to 1 (by dividing by the relative atomic mass) · Convert this number to the value of mass of the limiting reactant, given in the question, by multiplying by the value of the limiting reactant · Divide and multiply the ‘unknown’ relative atomic mass by the same values used for the limiting factor
Describe what is meant by concentration
The mass of solute in a set volume of solvent
State the equation for calculating concentration?
Concentration (g/dm3) = mass of solute (g) volume of solvent (dm3)