Chemistry Practice Flashcards: Units, Classifications, Atoms, and Molecules (Notes Pages 1-41)

41 Q&A flashcards covering properties, unit systems, conversions, atomic theory, formulas, empirical formulas, stoichiometry, and basic chemistry concepts from the provided notes.

1) Which of the following property is NOT an intensive property of a material? (a) density (b) color (c) combustible (d) melting point (e) mass

Mass (an extensive property)

2) Which statement is NOT a proper classification? (a) Apple juice is a homogeneous mixture. (b) Antimony is an element. (c) A snow cone is a heterogeneous mixture. (d) Steel is a compound. (e) Granite is a heterogeneous mixture.

Steel is a compound.

3) The density of Fe is 7.86 g/mL. Convert this to pounds per cubic foot. 1 foot = 30.48 cm; 1 lb = 453.6 g; 1 mL = 1 cm3.

Approximately 491 lb/ft3.

4) This summer I took a 4500 mile vacation in a van which gets 13 miles/gallon of gasoline. If the average price of gasoline on the trip was $1.27 per gallon, how many dollars did I spend on gasoline?

$440.

5) Permalloy steel is an alloy which is 21.2% Fe by mass. How many grams of Fe are present in 1.000 kg of steel? (Fe atomic mass: from periodic table)

212 g.

6) Which distance is greater? (Given: 1 Å = 1 x 10^-10 m) (a) 5 Å (b) 1 nm (c) 10^-6 mm (d) 100 pm

1 nm (b)

7) Which is an INCORRECT statement regarding unit systems? (a) One centimeter is 10^-2 meters, and one nanosecond is 10^-3 picoseconds. (b) The gram is defined to be the mass of 1 cm^-3 of liquid water at 4° C at atmospheric pressure. (c) The basic unit of length in the SI system is the meter. (d) A liter is slightly larger than a quart. (e) A cubic centimeter and a milliliter are the same volume.

a) One centimeter is 10^-2 meters, true; nanosecond is not 10^-3 picoseconds (false).

8) Which element is INCORRECTLY matched with its symbol? (a) Cu / copper (b) Pb / lead (c) K / potassium (d) Cr / chromium (e) B / bismuth

e) B / bismuth.

9) Denatured alcohol is ethyl alcohol to which various agents have been added to render it unfit for human consumption. A particular formula of denatured alcohol has 91% ethyl alcohol by mass. How many grams of ethyl alcohol are present in 500 g of this denatured alcohol?

455 g.

10) Which of the following materials has NOT been properly classified? (a) Soil is a homogeneous mixture. (b) Bromine is an element. (c) Water is a compound. (d) Steel is a homogeneous mixture. (e) Wood is a heterogeneous mixture.

a) Soil is a homogeneous mixture.

11) Which volume is greater? (Given: 1.00 in = 2.54 cm) (a) 2 x 10^-2 in^3 (b) 2 x 10^-6 m^3 (c) 1 cm^3 (d) 1 x 10^-3 L

b) 2 x 10^-6 m^3 (which is 2 cm^3)

12) An iodine atom has a diameter of 2.66 x 10^-10 m. If iodine atoms are lined up so that they are just touching, how many of them would it take to have a line 1.00 feet long? 1 foot = 30.48 cm = 0.3048 m.

c) 1.15 x 10^9 atoms.

13) Identify the compound below which is an ionic compound. (a) CH4 (b) H2O2 (c) Na2CO3 (d) NH3 (e) SO2

c) Na2CO3.

14) Identify the compound formula that is INCORRECT. (a) Ca3(PO4)2 for calcium phosphate (b) NaNO3 for sodium nitrate (c) K2CO3 for potassium carbonate (d) NH4SO4 for ammonium sulfate (e) KCl for potassium chloride

d) NH4SO4 is incorrect.

15) The number of protons in a silicon atom is: (a) 28 (b) 14 (c) 32 (d) 16 (e) 47

b) 14.

16) Which of the following statements are TRUE? 1) Under normal conditions nitrogen exists as a diatomic molecule. 2) Ca(NO)3 is an ionic solid. 3) An ionic solid always consists of cations and anions in equal numbers.

a) only 1.

17) Which of the following ion/name combinations is NOT CORRECT? (a) NO3^- / nitrate (b) SO4^2- / sulfate (c) NH4^+/ ammonium (d) PO4^3- / phosphate

c) NH4+/ammonia.

18) A doubly negative ion, symbolized by X^2-, forms a compound with a metal M, of the formula M2X. What is the charge on the metal, M?

+1.

19) Which of the following is the empirical formula for the compound iron(II) carbonate?

FeCO3.

20) Which of the following statements is incorrect? (a) A molecule is the smallest part of a compound that can have a stable independent existence. (b) Molecules that consist of more than one atom are called polyatomic molecules. (c) The atomic number of an element is defined as the number of neutrons in the nucleus. (d) Molecules of compounds are composed of more than one kind of atom. (e) The charge on an electron is negative and the charge on a proton is positive.

c) The atomic number is the number of protons, not neutrons.

21) Which of the following statements is not an idea from Dalton’s Atomic Theory? (a) An element is composed of extremely small indivisible particles called atoms. (b) All atoms of a given element have identical properties which differ from those of all other elements. (c) Atoms can only be transformed into atoms of another element by nuclear reactions. (d) Compounds are formed when atoms of different elements combine with each other in small whole-number ratios. (e) The relative numbers and kind of atoms are consistent in a given compound.

c) Atoms can only be transformed into atoms of another element by nuclear reactions.

22) Identify the compound formula that is INCORRECT. (a) Mg3(PO4)2 for magnesium phosphate (b) Fe(NO3)2 for iron(II) nitrate (c) NaCO3 for sodium carbonate (d) CuCl for cuprous chloride (e) AgBr for silver bromide

c) NaCO3 is incorrect (should be Na2CO3).

23) Which of the following ions does NOT have a -1 charge? (a) oxide (b) fluoride (c) hydroxide (d) nitrate (e) acetate

a) oxide (O^2- has -2).

24) Which of the following compounds is INCORRECTLY classified as ionic versus molecular? (a) H2O is a molecular compound (b) NO2 is an ionic compound (c) HCl is a molecular compound (d) CaO is an ionic compound (e) NH4Cl is an ionic compound

b) NO2 is not ionic; NO2 is covalent/molecular.

25) How many Hydrogen atoms are present in 27.0 g of H2O?

1.80 x 10^24 H atoms.

26) Calculate the formula weight of TNT, trinitrotoluene, which has a formula C6H2(CH3)(NO3)3.

275 g/mol.

27) Calculate the % Oxygen in NaHCO3, sodium bicarbonate.

57.1%.

28) Determine the simplest empirical formula of a compound with the following composition by mass: 29.1% Na; 40.5% S; 30.4% O. (Na = 23; S = 32; O = 16 g/mol)

Na2SO3.

29) An alkene hydrocarbon with an empirical formula of CH2 has a molecular weight of 98.2 amu. What is the true molecular formula for the compound?

C7H14.

30) How many grams of Nitrogen combine exactly with 6.0 grams of Hydrogen to produce NH3?

28.0 g.

31) Calculate the formula weight of iron(III) sulfate, Fe2(SO4)3.

399.9.

32) Calculate the % Oxygen by mass in glucose, C6H12O6.

53.3%.

33) Determine the simplest empirical formula of the drug methaqualone with the following composition by mass: 76.78% C; 5.64% H; 11.19% N; 6.39% O.

C16H14N2O.

34) An alkene hydrocarbon with an empirical formula of CH has a molecular weight of 26.0 amu. What is the true molecular formula for the compound?

C2H2.

35) Calculate the mass of a single molecule of water in grams.

3.0 x 10^-23 g.

36) How many moles of benzene (C6H6) are present in 7.81 grams of benzene?

0.100 mol.

37) Identify the INCORRECT statement: (a) One mole of water contains 6.022 x 10^23 H2O molecules. (b) There are 16.0 g in 1.00 mole of O2. (c) 12.0 g of Carbon have the same number of atoms as 14.0 g of Nitrogen. (d) 28.0 g of N2 have the same number of molecules as 32.0 g of O2. (e) A mole is the amount of substance having the same number of particles as 12 grams of pure Carbon-12.

b) 16.0 g in 1.00 mole of O2 is incorrect (O2 molar mass is 32 g/mol).

38) How many glucose molecules are present in 1.0 picogram (1 trillionth of a gram) of glucose, C6H12O6?

3.34 x 10^9 molecules.

39) Which has greater mass? (a) 1 atom of iron (b) 1 atom of Neon (c) 1 molecule of carbon dioxide (d) 1 molecule of water

a) 1 atom of iron.

40) In which sample are there more particles? (a) 1.0 g of gold (b) 1.0 g of carbon (c) 1.0 g of helium (d) 1.0 g of iron

c) 1.0 g of helium.

41) The fact that water is always found to be 89% Oxygen and 11% Hydrogen by mass is an example of:

The Law of Definite Proportions.