MIDTERM REVIEW. UNIT 1: Mass/Measurement

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1 MIDTERM REVIEW UNIT 1: Mass/Measurement Practice Problems 1. Circle the word/phrase that best fits the statement: A. [ PHYSICAL OR CHEMICAL] changes are changes in which the identity of the substance does not change. B. Chemical changes sometimes produce a [ GAS or GEL ] which can be observed by wafting. C. When two clear solutions mix, [NOTHING HAPPENS or A PRECIPITATE] forms producing a cloudy mixture. D. [QUANTITATIVE or QUALITATIVE] properties deal with numbers. E. [PURE SUBSTANCE or MIXTURE] contains only one type of atom or molecule. F. [REACTIVITY, DENSITY, or MELTING] is not a physical property. G. A mixture that is completely uniform in composition is a [HOMOGENEOUS or HETEROGENEOUS] mixture. 2. Indicate whether its a chemical or physical change: A. milk souring D. Chopping wood B. gasoline burning E. Breath fogging a mirror C. Ice melting 3. Indicate whether the material is a COMPOUND, ELEMENT, HOMOGENEOUS MIXTURE, or HETEROGENEOUS MIXTURE. A. hydrogen peroxide D. Sugar G. Ozone B. copper E. stainless steel C. a salad F. Nitrogen Gas 4. Indicate TRUE or FALSE. A. Elements can be separated easily into simpler substances. B. Compounds can be separated into simpler substances C. The properties of compounds are different from those of their components. D. Allotropes can be described as elements and compounds. E. Chemical properties are only observed when a substance undergoes a chemical change. 5. Identify the number of sig figs in each measurement: A g B. 70,420 ml C. 5 x 10 4 m/s D s E x10 14 ms 6. Convert the following: A. 3.5 Liters to Cubic Centimeters D km to m B kg to mg E. 750 microliters to liters C. 4 X nanoseconds to centiseconds F. 7 Megagrams to milligrams

2 7. Perform the following Arithmetic and place the answer in the correct number of sig figs (multiplication/division rules for significant figures trump addition/subtraction rules) A. (21 ml ml)/4x10 2 mg B. 734 m X 7.3 x 10 2 m 3.23x10 2 m C. ( kg kg) X 8.8x10-1 m 2 8. Calculate the number of seconds in the entire month of October. 9. Each chemistry teacher provides 6 test tubes to each lab group. In each class there are 12 lab groups, and the teacher has four classes. There are a total of 5 chemistry teachers. How many test tubes does the chemistry department provide for their students? (Use dimensional analysis) 10. A light year is the distance that light can travel in one year. If the sun is 150,000,000 km away, how many light years is the sun from the earth? Light travels at the speed of 3.0 X10 8 m/s. Place your answer in scientific notation. 11. What is the cost in dollars for the nails used to build a fence 125 meters long if it requires 30 nails per meter? Assume 40 nails are sold per box at a cost of $3.35 a box. 12. Determine the Volume that a 35.2 grams sample of carbon tetrachloride will occupy if it has density of 1.60 g/ml. 13. The density of ethanol is g/ml. What is the mass of a 100 ml sample?

3 UNIT 2: Nomenclature Practice Problems 1) Find the number of protons, neutrons and electrons in the following: Element Protons Neutrons electrons Copper zinc Carbon- 12 Carbon- 14 Sodium Phosphorus calcium silver tungsten mercury 2) What is average atomic mass of Lithium if 7.42% exists as 6 Li (6.015 g/mol) and 92.58% exists as 7 Li (7.016 g/mol)? 3. Neon has two major isotopes, Neon-20 and Neon-22. Out of every 250 neon atoms, 225 will be Neon-20 ( g/mol), and 25 will be Neon-22 ( g/mol). What is the average atomic mass of Neon? 4. What is the atomic mass of Hafnium if out of every 200 atoms, 10 have mass g/mol, 38 have mass g/mol, 54 have mass g/mol, 28 have mass g/mol, and 70 have mass g/mol? 5. In a sample of 200 Chlorine atoms, it is found that 151 are 35 Cl ( g/mol), and 49 are 37 Cl ( g/mol). What is the average atomic mass of Chlorine?

4 6. Without doing any math, are there more Bromine-79 atoms or more Bromine-80 atoms on earth? Explain your reasoning. 7. Find the molar mass of the following substances: Cu 2 SO 4 C 20 H 30 O 2 HNO 3 C 5 H 10 O 5 HC 2 H 3 O 2 Na NaCl 8. Name or write the formula of the following: potassium nitrate sodium phosphate ammonium phosphide Ammonium phosphate chromium (IV) chloride zinc sulfate aluminum oxide LiClO 2 NaMnO 4 Copper (II) oxide Fe 2O 3 9. How many atoms are in 208 grams of lead? How many atoms are in 12 grams of carbon? How many molecules are in 16 grams of methane (CH 4)? Explain the relationship between these numbers.

5 10. Do the following conversions: a) 36.5 grams of calcium to moles b) g of iron to moles c) 1.37 x 10 3 g of Cu to moles 11. A substance contains 26.57% potassium, 35.36% chromium, and 38.07% oxygen. What is the empirical and molecular formula if its molar mass is g/mol? What is the name of the compound/ 12. The compound propylene glycol is used in commercial antifreeze. What is the empirical and molecular formula if the percent composition is 47.37% carbon, 10.59% hydrogen and 42.04% oxygen and its molar mass is g/mol? 13. An acid is 2.04% hydrogen, 32.65% sulfur, and 65.31% oxygen. Find the empirical and molecular formula and name the acid. The molar mass is g/mol.

6 14. Write the name of the following acids: HF H 2SO 4 HCl HNO 3 HC 2H 3O 2 HNO 2 H 3PO 4 HClO 4 1) Balance the following reactions: UNIT 3: Chemical Reactions a) NaNO 3 + PbO! Pb(NO 3 ) 2 + Na 2 O b) AgI + Fe 2 (CO 3 ) 3! FeI 3 + Ag 2 CO 3 c) C 2 H 4 O 2 + O 2! CO 2 + H 2 O d) ZnSO 4 + Li 2 CO 3! ZnCO 3 + Li 2 SO 4 e) V 2 O 5 + CaS! CaO + V 2 S 5 f) Mn(NO 2 ) 2 + BeCl 2! Be(NO 2 ) 2 + MnCl 2 g) AgBr + GaPO 4! Ag 3 PO 4 + GaBr 3 h) H 2 SO 4 + B(OH) 3! B 2 (SO 4 ) 3 + H 2 O i) S 8 + O 2! SO 2 j) Fe + AgNO 3! Fe(NO 3 ) 2 + Ag 2) Determine the type of reaction shown and predict the products of each. If the reaction does occur, balance it. If a reaction will not occur, explain why not: a) Ag 2 SO 4 + NaNO 3! b) NaI + CaSO 4!

7 c) HNO 3 + Ca(OH) 2! d) AlCl 3 + (NH 4 ) 3 PO 4! e) Pb + Fe(NO 3 ) 3! f) Na + CaSO 4! 3) Double Displacement: Predict the products of the reactions below (names and formulas), balance the equations, and write the complete ionic and net ionic equations if the reaction occurs. Identify the spectator ions by circling them in the complete ionic equation. a) silver nitrate + potassium phosphate! b) copper (II) bromide + aluminum chloride! c) sodium chromate + copper (II) nitrate! d) carbonic acid + potassium sulfide! e) nitrous acid + barium hydroxide!

8 4) Balance and determine the products for the following single displacement reactions: a) Al + Fe(NO 3 ) 2! b) Na 2 SO 4 + Pb! c) BaCl 2 + F 2! d) Fe + HC 2 H 3 O 2! e) Co + AuPO 4! 5) Describe the difference between a synthesis and a decomposition reaction. 6) How can you identify a combustion reaction by looking at the reactants and products? 7) Identify the reactions below as single or double displacement, decomposition, synthesis, or combustion: a) Mg + HCl MgCl 2 + H 2 b) Na + MgF 2 NaF + Mg c) Cl 2 + KI KCl + I 2 d) NaCl Na + Cl 2 e) Na + O 2 Na 2 O f) Na + HCl H 2 + NaCl g) K + Cl 2 KCl h) Ca + O 2 CaO

9 i) H 2 O 2 2 H 2 O + O 2 j) N 2 + 3H 2 NH 3 k) Cu 2 O + C Cu + CO 2 l) CH 4 + O 2 CO 2 + H 2 1. What is a mole? UNIT 4: Stoichiometry 2. What is stoichiometry? Why is it important to a chemist? 3. Calculate the mass of one mole of a) water b) acetic acid c) oxygen gas d) zinc phosphate 4. What is Avogadro s number? How is it related to a mole? 5. Calculate the number of grams in each of the following. a. 1.5 moles of potassium oxide

10 b. 5.9 moles of sodium c x atoms of copper d x 10-3 moles of silver nitrate 6. Calculate the number of particles (atoms, formula units or molecules) of each of the following: a mol of Au b. 3.5 mol of C 3H 8 c g of sulfur d. 5.0 g of Na 2CO 3

11 7. Complete the questions for the following reaction. Use dimensional analysis. C 3H 8 + 5O 2 3CO 2 + 4H 2O a. How many moles of oxygen will be needed to react with 0.38 mol of propane, C 3H 8? b. How many moles of water will be produced from the combustion of 50.0 grams of propane? c. How many grams of carbon dioxide is produced from the combustion of 25.5 grams of propane? d. How many molecules of carbon dioxide will be produced from the consumption of 5.6 grams of oxygen? e. How many molecules of propane is burned if g of propane is burned?

12 8. In a reaction of 0.26 mol of NaCl with 0.18 mol of Pb(NO 3) 2, how many grams of lead(ii) chloride will be produced? What is the limiting reagent? 2 NaCl + Pb(NO 3) 2 PbCl NaNO 3 9. Identify the limiting reactant when mol of magnesium reacts with 6.4 g of oxygen to produce magnesium oxide. Which is the limiting reagent? 2 Mg + O2! 2 MgO 10. If 3.40 g of magnesium oxide is actually produced from the reaction in #9, what is the percent yield? 11. In a reaction between lead (II) nitrate and copper (II) bromide, do the following: a) write the formulas for the reactants and the products and balance the equation b) If 0.67 moles of copper (II) bromide react with 0.52 grams of lead (II) nitrate, how many grams of lead(ii) bromide will be produced? c) Which reactant is the limiting reagent?

13 In addition, any of the material from this week will also be on the midterm (calculating molarity, making solutions using molarity, titration and naming molecular compounds) g of aluminum metal reacts with 10.0 ml of 1.5 M hydrobromic acid, as shown below Al + HBr a. Determine if the reaction happens. If it does, write the formulas and names of the products and balance the equation. b. What kind of reaction is this? c. Using the amounts of aluminum metal and HBr from the equation, determine which one is the limiting reactant. 2. You are asked to make ml of a M solution of zinc sulfate. How many grams of zinc sulfate do you need? 3. You titrated 10.0 ml of HCl with 9.8 ml of 2.0 M NaOH. What is the molarity of the HCl?

14 4. Name the following compounds (some are molecular or ionic). Name any acids using acid naming rules: a. N 2 O 3 b. CS 2 c. P 2 O 5 d. SO 2 e. Fe 2 O 3 f. HBr g. CaCO 3