PO1-You should be able to define and give examples of the following terms and concepts:
PO2-You should be able to balance a chemical equation.
Example 1- The reactionis not balanced. The reactants contain 4 H atoms, while the products contain just 3. Likewise, the reactants contain just 2 Cl atoms, while the products contain 3. Increasing the coefficient of the HCl to 2 will make the number of H atoms in the reactants and products equal:. But the number of Cl atoms in the reactants is only half that in the products. So, to balance the reaction it is necessary to increase the coefficient of the Cl2 to 2:.
Self-test 1- Balance the following equation by entering the correct coefficient for each reactant and product in the following equation. You should enter 1 if that is the correct coefficient.HCl + Mg(OH)2 ----> MgCl2 + H2O
Self-test 2- Balance the following equation by entering the correct coefficient for each reactant and product in the following equation. You should enter 1 if that is the correct coefficient.C2H6 + O2 ----> CO2 + H2O
Self-test 3- Balance the following equation by entering the correct coefficient for each reactant and product in the following equation. You should enter 1 if that is the correct coefficient.AlCl3 + Ba(OH)2 ----> BaCl2 + Al(OH)3
PO3-You should be able to calculate the molecular weight or the formula weight of a compound.
Example 1-To calculate the molecular weight of ethane, C2H6, multiply the number of C atoms by the atomic weight of C. Then multiply the number of H atoms by the atomic weight of H. Then add the two numbers:.
Example 2-To calculate the formula weight of calcium phosphate, Ca3(PO4)2 , multiply the number of Ca, P, and O atoms by the atomic weights of Ca, P, and O, respectively. Add the three numbers:.
Self-test 4- Calculate the molecular weight of methanol, CH3OH. Enter your answer to the nearest 0.1 amu.amu
Self-test 5- What is the formula weight of potassium carbonate, K2CO3? Enter your answer to the nearest 0.1 amu. amu
PO4-You should be able to convert the mass of a compound to its equivalent amount in moles and vice versa.
The molecular formula for aspirin is C9H8O4. A regular strength aspirin tablet contains 0.300 g of aspirin. To calculate the number of moles of aspirin this equals, divide the mass of the aspirin by the molar mass of aspirin.
First, calculate the molecular weight or molar mass: .
Then, divide the mass of the aspirin by the molar mass: .
Example 2-To calculate the mass of 0.1037 mol of calcium phosphate, Ca3(PO4)2 , multiply the number of moles by the molar mass: (0.1037 mol x 310.3 g/mol) = 32.18 g.
Self-test 6- Isoamyl acetate is, CH3CO2CH2CH2CH(CH3)2, contributes to the flavor of ripe bananas. How many moles are there in 50.21 g of isoamyl acetate?mol
Self-test 7- If you had 1.03 moles of sulfuric acid, H2SO4, what mass of material would you have?g
PO5-Given the mass of one of the reactants in a balanced equation, you should be able to calculate the mass any other reactant required. You should also be able to calculate the theoretical yield of any of the products of the reaction
Example 1-Previously we saw how to balance the equation for the reaction of methane with dichlorine:. To calculate the mass of Cl2 required to completely react with 18.2 g of CH4 requires three steps: 1. Convert 18.2 g to its equivalent value in moles. 2. Use the coefficients from the balanced equation to determine the conversion factor required to convert the number of moles of CH4 used to the number of moles of Cl2 required. 3. Convert the number of moles of Cl2 required to its equivalent mass in grams:
Example 2-We can calculate the theoretical yield of dichloromethane, CH2Cl2, that can be formed in this reaction in a similar manner:
Self-test 8- What is the theoretical yield of HCl that can be formed in the reaction of 1.14 mol of methane with 2.28 mol of dichlorine?g
Self-test 9- What mass of CH4 is required to produce 20.1 g of CH2Cl2 in this reaction?g
Self-test 10- 2C2H6 + 7O2 --> 4CO2 + 6H2O is the balanced equation that describes the combustion of ethane. The formula weight of ethane is 30.07 g/mol. Therefore, the mass of 2 moles of ethane equals (2 mol)(30.07 g/mol) = 60.14 g. Complete combustion of 2 moles of ethane produces 6 moles of water. This amount of water weighs (18.02 g/mol)(6 mol) = 108.12 g.The molar quantities and the equivalent masses of all the compounds involved in this reaction when starting with 2.00 moles of ethane are shown in the 3rd row of the table below. Note that once you have a balanced equation, you need to know only one of the quantities in any row of this table in order to calculate all of the other values. In the 4th row, half of the values are shown for the case where 1.00 moles of C2H6 are used. In the 8th row of the table the mass of C2H6 is given as 50.00 g. This is equivalent to (50.00 g/30.07 g/mol) = 1.66 mol. The number of moles of O2 needed is going to be (7/2)(1.66) = 5.82 mol, and the equivalent mass of O2 is (5.82 mol)(32.00 g/mol) = 186.24 g.
Fill in the missing information in this table. Use the following molecular weights: C2H6 = 30.07 g/mol, O2 = 32.00 g/mol, CO2 = 44.01 g/mol, H2O = 18.02. Round the mass of each compound to the nearest hundredth of a gram after you have completed each calculation. Decimal values must have a leading zero; i.e. enter .33 as 0.33.
PO6-You should understand how to calculate the oxidation number of an atom in a molecular compound.
Example 1-The oxidation number of C in CH4 is -4: Since H is a Group 1 element, its normal oxidation level is +1. (4) x (+1) = +4, so the oxidation number of the C atom must be -4 since the sum of the oxidation levels of all the atoms in a neutral molecule must add up to zero.
Example 2-The oxidation number of C in CCl4 is +4: Since Cl is a Group 7 element, its normal oxidation level is -1. (4) x (-1) = -4, so the oxidation number of the C atom must be +4.
Example 3-The oxidation number of N in NO2 is +4. Since O is a Group 6 element, its normal oxidation level is -2. (2) x (-2) = +4, so the oxidation number of the N atom must be +4.
Example 4-The oxidation number of O in F2O is +2. The normal oxidation state of O is -2. Since F is a Group 7 element, its normal oxidation level is -1. Since F is more electronegative than O, its oxidation level determines the oxidation level of the O atom. (2) x (-1) = -2, so the oxidation number of the O atom is +2.
Example 5-The oxidation number of Al in Al2O3 is +3. The normal oxidation state of O is -2. (3) x (-2) = -6, so the oxidation number of each Al atom is (+6/2) = +3.
Self-test 10- What is the oxidation state of the Br atom in Br2? 01 2 -2
Self-test 11- What is the oxidation state of the C atom in CH3OH? 01 2 -2
PO7-You should be able to identify the species that is oxidized and the species that is reduced in a redox reaction.
Example 1-The combustion of natural gas may be described by the equation. The oxidation number of the carbon in methane is -4, while the oxidation number of the carbon in carbon dioxide is +4. Since its oxidation number increases, the carbon atom in methane is oxidized when the methane is converted into carbon dioxide. The oxidation number of the oxygen atom in dioxygen is 0. In carbon dioxide and in water it is -2. So the oxidation number of the oxygen has decreased and we say that the oxygen atoms in dioxygen have been reduced.
Self-test 12- Which atom is oxidized in the reaction?ZnMn O Zn and Mn
Self-test 13- Which atom is reduced in the reaction?NaH S none of the atoms is reduced.
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