Page 222 - Chemistry eBook

Al(s) 􏰀 CuSO4(aq) → Al2(SO4)3(aq) 􏰀 Cu(s)
52 Identify the type of chemical reaction represented by the equation. [1]
53 Balance the equation in your answer booklet, using the smallest whole-number
coefficients. [1]
Sample Regents Questions
54 Explain why the equation represents a chemical change. [1]
55 Determine the total mass of Cu produced when 1.08 grams of Al reacts completely with
9.58 grams of CuSO4 to produce 6.85 grams of Al2(SO4)3. [1]
Base your answers to questions 56 through 59 on the information below.
A total of 1.4 moles of sodium nitrate is dissolved in enough water to make 2.0 liters of an aqueous solution. The gram-formula mass of sodium nitrate is 85 grams per mole.
56 Write the chemical formula for the solute in the solution. [1]
June 2012 #55
57 Showanumericalsetupforcalculatingthemassofthesoluteusedtomakethesolution. [1]
58 Compare the boiling point of the solution at standard pressure to the boiling point of
H2O at standard pressure. [1]
Answer
59 Determine the molarity of the solution. [1]
3.81 grams of ‘Cu’
Explanation: First let’s figure out the equation. Then we can find the answer.
• “Determine the total mass of ‘Cu’ produced”: This means that ‘Cu’ is a product of the reaction and will
be on the right side of the equation. We don’t know how many grams there are, so stick in a question mark
there: _ ? Cu
• “... when 1.08 grams of ‘Al’ react completely with 9.58 grams of CuSO4”: This means that ‘Al’ and CuSO4
are being added together to form a reaction. So we will place them on the left side of the equation:
P.S./Chem.–June ’12 [8] 1.08 grams Al + 9.58 grams of CuSO4 _ + ? Cu
• “... to produce 6.85 grams of Al2(SO4)3”: “To produce” means that Al2(SO4)3 is a product and will be on the right side of the equation.
1.08 grams Al + 9.58 grams CuSO4 6.85 grams of Al2(SO4)3 + ? grams of Cu
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