We will not cover solution stoichiometry on Exam 1.

Transcription

1 Chemistry 1A Fall 2017 Exam 1 Review I. Chapter 1 Terms: macroscale and nano scale atoms and molecules elements and compounds (nanoscale and macroscale definitions) mixtures structure of solid, liquid, gas (nanoscale, draw pictures) Scientific Method--observations, law, hypothesis, experiment, theory (MEMORIZE these, be able to define and use them) dimensional analysis, problem solving density (MEMORIZE the formula that defines density) significant figures metric system: nano-, milli-, centi-, kilo- (MEMORIZE these prefixes) ***************************************************************************** Quiz 2 Material Starts Here II. Chapter 2--Atoms, Molecules, and Ions Atomic theory nuclear atom, electrons, protons, neutrons MEMORIZE charge and approximate mass for each particle isotopes, atomic number, mass number calculate average mass from isotope abundance periodic table periods, groups, metals, nonmetals, metalloids MEMORIZE three group names: alkali metals, halogens, inert gases chemical formulas MEMORIZE: Seven diatomic elements: H 2, N 2, O 2, F 2, Cl 2, Br 2, I 2 MEMORIZE: NH + 4, NO - 3, CO 2-3, SO 2-4, PO 3-4, OH - -, C 2 H 3 O 2 (with names: ammonium, nitrate, carbonate, sulfate, phosphate, hydroxide, acetate ions) MEMORIZE formulas and names for acids: HCl, HNO 3, H 2 SO 4, H 3 PO 4, HC 2 H 3 O 2 MEMORIZE formulas for water, carbon dioxide, carbon monoxide, ammonia Write chemical formulas for ionic compounds Quiz 2 Material Ends Here ***************************************************************************** IV. Chapter 4 Balancing Equations balancing chemical equations Predicting products: burning, precipitation, acid-base, single replacement (We will not cover dilution, net ionics, or oxidation-reduction on Exam 1.) V. Chapter 3--Stoichiometry mole Avogadro's number (don t memorize the number, just use) molar mass (molecular weight), converting grams moles percent composition empirical formula g mole mole g (stoichiometry) We will not cover solution stoichiometry on Exam 1.

2 Chabot College Chemistry 1A Fall 2014 Name Exam 1 This exam has 6 pages, none of them blank. Show all your work and use correct significant figures throughout. Please turn your cell phone all the way off. Helpful Information N Av = 6.02 x pico = 1x kg = 2.20 pounds 1. (6 points) If given the name, give the formula; if given the formula, give the name. ammonia sodium sulfide KNO 3 calcium phosphate 2. (6 points) Conversions m = mm 4.98 ml = L 26.4 mm = nm g = mg 3. (6 points) Fill in the following table (be sure to include the mass number A and any charge on all of your atomic symbols): Symbol Number of protons Number of neutrons Number of electrons Charge 235 U

3 p. 2 Name 4. (12 points) Write balanced chemical equations for the following reactions (no net ionics): a) Ethyl furoic acid (C 7 H 8 O 3 ) is burnt. b) Solutions of iron(iii) nitrate and potassium hydroxide are mixed. A precipitate forms. c) Solutions of barium hydroxide and phosphoric acid are mixed. d) Hydrochloric acid reacts with a piece of magnesium metal. 5. (5 points) What is the difference between an element and a compound? You may answer this using a nanoscale perspective or macroscale perspective. Circle the one you chose to use: Nanoscale or Macroscale

4 p. 3 Name 6. (12 points) Suppose I have a box that contains four atoms of magnesium metal and eight oxygen molecules. a) Write a balanced equation for the reaction that will occur when the two react. b) Draw a picture of the box contents before and after the reaction. Before After 7. (4 points) Carry out the following arithmetic operations. Show the correct answer with correct significant figures (and units, if applicable): = g g g 100%

5 p (6 points) Classification Name a) State the group and period: Atom Group Period P b) Classify the following as either ionic or covalent: NH 3 SO 2 AlCl 3 BrCl Ionic Covalent 9. (10 points) C 12 H 4 Cl 4 O 2 Dioxin (structure above) has been identified as "the most toxic synthetic chemical known to man". Dioxin was a contaminant at Love Canal and was the contaminant of concern in agent orange (Vietnam). Municipal waste incinerators also emit dioxin. Currently, the EPA calculates that in order to keep your chances of getting cancer caused by dioxin below 1 in 1 million, you should have a daily intake of dioxin no greater than.006picograms per kg body weight. What is the maximum number of dioxin molecules you can ingest in one day without exceeding this limit?

6 Name 10. (3 points) Multiple Choice and Short Answer a) Jorge is an excellent student and always does things correctly. When we look in his lab notebook, we find that his data are written in (circle all acceptable answers): i) pencil ii) invisible ink iii) ink iv) erasable ink v) pencil, and he will write over it later in ink. b) When Jorge is writing down his buret readings for the first time, he writes them (circle all acceptable answers): i) on a paper towel ii) on the back of his hand iii) in his lab book iv) in the margins of the lab instructions v) His partner writes down the data, Jorge will get it from his partner later. vi) Jorge is so smart he doesn t have to write anything down, it is all in his head. c) Here s the short answer part: If you are using a scoopula to transfer a chemical from the original container onto your weighing boat, how can you make sure that none is spilled on the balance? p (12 points) Aluminum reacts with bromine to form aluminum bromide. If 3.00 g of aluminum is mixed with 20.0g of bromine, how many grams of aluminum bromide can be formed?

7 p. 6 Name 12. (10 points) What volume of magnesium metal would be required to react completely with 55.5g of nitric acid? 13. (8 points) Compound Z (found in apples and other fruits) has the following elemental analysis: C 35.83%, H 4.51%, O 59.66%. What is the empirical formula? Extra Credit: There are two naturally occurring isotopes of gallium: 69 Ga with a mass of amu, and 71 Ga with a mass of amu. Calculate the percentage abundance of each isotope.