C3 Quantitative Chemistry

Question 1

<p>What is the <b>Law Of Conservation of Mass</b>?</p>

Answer 1

<p>The Law of Conservation of Mass states that the total mass of reactants is equal to the mass of the product</p>

<p>No mass can be created or destroyed in a reaction</p>

Question 2

<p>What is <b>Relative Atomic Mass (A_r)</b>?</p>

Answer 2

<p>Relative Atomic Mass is the average mass of the atom</p>

Question 3

<p>How do you calculate Moles of a substance?</p>

Answer 3

<p>Moles (mol) = Mass (g) / Relative Formula Mass (M_r)</p>

Question 4

<p>What is <b>Relative Formula Mass (M_r)</b></p>

Answer 4

<p>Relative Formula Mass is the sum of the Relative Atom Masses of the elements in the substance</p>

Question 5

<p>How do you calculate <b>Concentration of a solution</b>?</p>

Answer 5

<p>Concentration (g/dm³) = Mass (g) ÷ volume (dm₃)</p>

<p>Concentration (mol/dm³) = Moles (mol) ÷ volume (dm₃)</p>

Question 6

<p>How do you calculate <b>Percentage Yield</b>?</p>

Answer 6

<p>Percentage Yield = Real Yield / theoretical Yield × 100</p>

Question 7

<p>What is <b>Atom Economy</b>?</p>

Answer 7

<p>Atom Economy is the conversion efficiency of a chemical process</p>

Question 8

<p>How do you calculate Atom Economy?</p>

Answer 8

<p>Atom Economy(%) = relative molecular mass of desired products ÷ total relative molecular mass of all reactants × 100</p>

Question 9

<p>How much is one mole?</p>

Answer 9

<p>One mole is 6.02x10²³ atoms of a substance</p>

Question 10

<p>What is a limiting reactant?</p>

Answer 10

<p>The limiting reactant is the reactant that is completely used up and the reaction stops because it is used up</p>

Question 11

<p>How do you make sure a substance is fully reacted?</p>

Answer 11

<p>To make sure a substance is fully reacted, an excess amount of the other reactant is used</p>

Question 12

<p>Why can an incomplete reaction happen?</p>

Answer 12

<ul><li>The reaction is very slow and hasn't been given enough time to happen</li><li>The reaction is reversible and some of the products have been converted back into reactants</li></ul>

Question 13

<p>Why is Percentage Yield always less than 100%?</p>

Answer 13

<ul><li>The reaction may be incomplete</li><li> Extraction<ul><li>It's difficult to separate the product from the reaction mixture</li></ul></li><li>Waste<ul><li>Some chemicals will be stuck to apparatus and wasted</li></ul></li><li>Side Reactions<ul><li>Unexpected reactions may happen which creates an unintended product</li></ul></li></ul>

Question 14

<p>What is <b>Theoretical Yield</b>?</p>

Answer 14

<p>The theoretical yield is the maximum mass of a product that could possibly be created from a reaction</p>

Question 15

<p>What is Actual Yield?</p>

Answer 15

<p>The actualyield is the mass of the desired product obtained from a reaction</p>

Question 16

<p>Why are reaction pathways with high atom economies good?</p>

Answer 16

<ul><li>Cost effectiveness</li><ul><li>Using the smallest amount of reactants saves money</li></ul><li>Low Waste</li><ul><li>A high atom economy means less waste products are produced</li></ul></ul>

Question 17

<p>What do we need to know about a solution to calculate the amount of a solute present?</p>

Answer 17

<ul><li>The solution's concentration</li><li>The solution's volume</li></ul>

Question 18

<p>What is the volume of 1 mole of any gas at room temperature and pressure</p>

Answer 18

<p>24dm³</p>