Chemistry Q2 Amazing Benchmark Review

Example 1: Nitrogen monoxide gas reacts with hydrogen gas to form nitrogen gas and water. NO (g) + H2 (g)  N2 (g) + H2O (l) What is the coefficient for NO? __NO (g) + 2H2 (g)  N2 (g) + 2H2O (l)

Example 2: Lithium has a mass of 6.9 g / mole. – 6.9 g = 1 mole Li Scandium has a mass of 45 g / mole. – 45 g = 1 mole Sc Tungten has a mass of 184 g / mole. – 184 g = 1 mole W

Example 3: 2Li (s) + 1Cl2 (g)  2LiCl (s) Mole Ratio: 2 mol Li = 1 mol Cl2 or 2 mol Li 1 mol Cl2 2 mol Li = 2 mol LiCl or 2 mol Li 2 mol LiCl

Example 5: 2Li (s) + 1Cl2 (g)  2LiCl (s) If you consumed 10 moles Li in the chemical reaction, how many moles of Cl2 gas would you need to take reaction to completion? 5 moles Cl2 How many moles of LiCl would you produce? 10 moles LiCl

Example 6: 2NO (g) + 2H2 (g)  1_X__ + 2H2O (l)4H2O 2N What would be compound X? N 2

Example 7: Calculate Molar Mass of H2O. 2H x 1 g/mol = 2 g/mol 1O x 16 g/mol = 16 g/mol molar mass = 18 g/mol H2O

Example 8 Be able to do Stoichiometry. Convert from grams to moles. Convert from moles to atom or molecules. Avogadro’s # = x atoms (molecules) 1 mol K Avogadro’s # = x molecules 1 mol CH4

Example 9: Exothermic Rxn Endothermic Rxn Negative number Positive number -212 kj 57 kj

Example 10 In exothermic reaction, heat releases into surrounding which leads to lower heat or PE of the system/reactant.

Example 11 In endothermic reaction, PE of the reactant or system (water) is lower than the PE of the product (ice or steam).

Example 12 Understanding Moles: One of the values of mole is that every mole of any element has the same number of atoms in it. samples 1 mol H = g H 1 mol O = 16 g O H H H H H H O O O O O O

Example 13 Atomic mass (g) of all the elements on Periodic Table represents the average weight of all their isotopes. For example: Carbon-12, Carbon-10, and Carbon g + 10 g + 14 g = 36 g divided by 3 = 12 g/mol C

Example 14 Heating/cooling curve at constant rate – From Liquid to Steam: plateau at boiling is longer. – From Liquid to Ice: plateau at freezing is shorter.