1 Mg, 2 O, and 2 H 2 Mg, 2 O, and 2 H 6 Mg, 6 O, and 6 H 3 Mg, 6 O, and 6 H

1 Mg, 2 O, and 2 H 2 Mg, 2 O, and 2 H 6 Mg, 6 O, and 6 H 3 Mg, 6 O, and 6 H

  NaS   NaS2   Na2S    Na2S2

  NaS   NaS2   Na2S    Na2S2

 too few significant figures are used in the problem’s calculations. there are experimental uncertainties in the measurements.  coefficients are always rounded to integers so it doesn’t matter.  approximations were made in the calculations.

 too few significant figures are used in the problem’s calculations. there are experimental uncertainties in the measurements.  coefficients are always rounded to integers so it doesn’t matter.  approximations were made in the calculations.

1.57 mol H2 reacts. 0.785 mol H2 reacts. Cannot be determined without more information. 3.14 mol H2 reacts.

1.57 mol H2 reacts. 0.785 mol H2 reacts. Cannot be determined without more information. 3.14 mol H2 reacts.

The following equation is unbalanced: CS2 + O2 CO2 + SO2 What is the correct balanced equation? CS2 + 2 O2 → CO2 + 2 SO2 2 CS2 + 12 O2 → 2 CO2 + 4 SO2 CS2 + 3 O2 → CO2 + 2 SO2 CS2 + 6 O2 → CO2 + 2 SO2

Correct Answer: CS2 + 2 O2 → CO2 + 2 SO2 2 CS2 + 12 O2 → 2 CO2 + 4 SO2 This is the only case where the number of each type of atom is the same on both the reactant and product sides of the equation.

Which of the following is the correct, balanced chemical equation for the combustion of ethanol (C2H5OH)? C2H5OH + O2 → CO2 + H2O C2H5OH + 3 O2 → 2 CO2 + 3 H2O C2H5OH + 6 O2 → 4 CO2 + 6 H2O 2 C2H5OH + 7 O2 → 4 CO2 + 6 H2O O O O C

Correct Answer: C2H5OH + O2 → CO2 + H2O C2H5OH + 3 O2 → 2 CO2 + 3 H2O

If the empirical formula of a compound is C2H2N but the molecular weight is 160 g/mol, what is the molecular formula? C2H2N C4H4N2 C6H8N3 C8H8N4 None of the above choices is correct.

Correct Answer: C2H2N C4H4N2 C6H8N3 C8H8N4 None of the above choices is correct. FW C2H2N = (24 + 2 + 14) g/mol = 40 g/mol MW/FW = 160/40 = 4 Thus, molecular formula is 4 empirical formula 4(C2H2N) = C8H8N4

How many fluorine atoms are present in 2.0 moles of AlF3? 3.0  1023 6.0  1023 1.2  1024 3.6  1024 None of the above answers is correct.

Correct Answer: 3.0  1023 6.0  1023 1.2  1024 3.6  1024 None of the above answers is correct. (2.0 moles AlF3)(6.0  1023 molecules AlF3/mole AlF3) (3 atoms F/1 molecule AlF3) = 3.6  1024

Which of the following samples has the largest number of atoms? 28 g Si 28 g CO 28 g N2 15 g C2H4 All of the above have equal numbers of atoms.

Correct Answer: 28 g Si 28 g CO 28 g N2 15 g C2H4 All of the above have equal numbers of atoms. 28 g Si has 1 mole of atoms, whereas 28 g of CO and N2 have 2 moles of atoms, even though they also have only 1 mole substance. However, there are 6 atoms for every 1 mole of C2H4, so in this case there are slightly more than 3 moles worth of atoms.

The molecular mass for the compound, XClO3, is 122. 5 amu The molecular mass for the compound, XClO3, is 122.5 amu. The atomic mass of X is equal to ____ amu, which is the element ____. 1.0; H 6.9; Li 23.0; Na 39.1; K 85.5; Rb

MW = 122.5 amu = AW X + AW Cl + 3(AW O) Correct Answer: 1.0; H 6.9; Li 23.0; Na 39.1; K 85.5; Rb MW = 122.5 amu = AW X + AW Cl + 3(AW O) 122.5 amu  AW Cl  3 (AW O) = AW X 122.5 amu  (35.45 amu)  3 (16.0 amu) = AW X 122.5  35.45 amu  48.0 amu = AW X AW X = 39.1 amu

When the chemical equation, C4H10(g) + O2(g) H2O(g) + CO2(g), is balanced, the stoichiometric coefficients are, respectively: 1, 4, 5, 4 2, 13, 10, 8 2, 9, 8, 10 2, 7, 4, 5

Correct Answer: 1, 4, 5, 4 2, 13, 10, 8 2, 9, 8, 10 2, 7, 4, 5

CH4(g) + 2 O2(g) 2 H2O(l) + CO2(g) The combustion of methane (CH4) is shown below: CH4(g) + 2 O2(g) 2 H2O(l) + CO2(g) How many grams of water are produced in the combustion of 1.0 moles of methane? 16 g 32 g 36 g 48 g

Correct Answer: 16 g 32 g 36 g 48 g (1.0 mole CH4)(2 moles H2O/1 mole CH4)(18 g H2O/1 mole H2O) = 36 g

There is a molar excess of carbon, not all carbon is consumed. 0.5 mol of carbon is combusted with 1.0 mol of oxygen gas. Which of the following statements is correct? There is a molar excess of carbon, not all carbon is consumed. There is a molar excess of oxygen, not all oxygen is consumed. There are stoichiometrically equivalent amounts of carbon and oxygen gas.

Correct Answer: There is a molar excess of carbon, not all carbon is consumed. There is a molar excess of oxygen, not all oxygen is consumed. There are stoichiometrically equivalent amounts of carbon and oxygen gas. C and O2 react in a 1:1 stoichiometric ratio, therefore there must be excess O2 because there was a larger initial number of moles of it.

0.5 mol of carbon is combusted with 1.0 mol g of oxygen gas. How many moles of carbon dioxide are produced? 1.5 mol 1.0 mol 0.5 mol 2.0 mol

Correct Answer: 1.5 mol 1.0 mol 0.5 mol 2.0 mol C and O2 react in a 1:1 stoichiometric ratio, therefore C must be the limiting reagent and O2 must be the excess reagent. Initially, (0.5 moles C)(1 mole CO2/1 mole C) = 0.5 mole CO2

24.0 g of carbon are combusted with 32.0 g of oxygen gas. How many grams of carbon dioxide are produced? 56.0 g 88.0 g 28.0 g 44.0 g

Correct Answer: 56.0 g 88.0 g 28.0 g 44.0 g C and O2 react in a 1:1 stoichiometric ratio. Initially, (24.0 g C)  (1 mole C/12.0 g C)  (1 mole CO2/1 mole C) = 2.0 mole CO2 (32.0 g O2)  (1 mole O2/32.0 g O2)  (1 mole CO2/1 mole O2) = 1.0 mole CO2 Thus, O2 is limiting, and 1.0 mole of CO2 is 44.0 g.

3. 0 moles Mg are combusted with 2. 0 moles O2 3.0 moles Mg are combusted with 2.0 moles O2. What is the limiting reagent and how many moles of the excess reagent remain? Magnesium, 0.5 mole Magnesium, 1.0 mole Oxygen gas, 0.5 mole Oxygen gas, 1.0 mole

Correct Answer: Magnesium, 0.5 mole Magnesium, 1.0 mole Oxygen gas, 0.5 mole Oxygen gas, 1.0 mole Mg and O2 react in a 2:1 stoichiometric ratio. Initially, (3 mole Mg)(2 mole MgO/2 mole Mg) = 1.5 mole MgO (2 mole O2)(2 mole MgO/1 mole O2) = 4 mole MgO Thus, Mg is limiting, and 3 mol Mg will consume 1.5 mol of O2, leaving 0.5 mole of O2.

How many oxygen atoms are present in MgSO4 • 7 H2O?

How many oxygen atoms are present in MgSO4 • 7 H2O?

How many sulfur atoms are present in 1.0 mole of Al2(SO4)3? 6.0 x 1023 sulfur atoms 1.8 x 1024 sulfur atoms

How many sulfur atoms are present in 1.0 mole of Al2(SO4)3? 6.0 x 1023 sulfur atoms 1.8 x 1024 sulfur atoms

If you have equal masses of the following metals, which will have the most number of atoms? Lithium Sodium Potassium Rubidium Calcium An alkali metal Ca in H2O

If you have equal masses of the following metals, which will have the most number of atoms? Lithium Sodium Potassium Rubidium Calcium An alkali metal Ca in H2O

How many moles of oxygen gas are required to react completely with 1 How many moles of oxygen gas are required to react completely with 1.0 mole NO? 2 NO (g) + O2 (g) 2 NO2 (g) 0.5 mol O2 1.0 mol O2 1.5 mol O2 2.0 mol O2 2.5 mol O2

How many moles of oxygen gas are required to react completely with 1 How many moles of oxygen gas are required to react completely with 1.0 mole NO? 2 NO (g) + O2 (g) 2 NO2 (g) 0.5 mol O2 1.0 mol O2 1.5 mol O2 2.0 mol O2 2.5 mol O2

If 10. 0 moles of NO are reacted with 6 If 10.0 moles of NO are reacted with 6.0 moles O2, how many moles NO2 are produced? 2 NO (g) + O2 (g) 2 NO2 (g) 2.0 mol NO2 6.0 mol NO2 10.0 mol NO2 16.0 mol NO2 32.0 mol NO2

If 10. 0 moles of NO are reacted with 6 If 10.0 moles of NO are reacted with 6.0 moles O2, how many moles NO2 are produced? 2 NO (g) + O2 (g) 2 NO2 (g) 2.0 mol NO2 6.0 mol NO2 10.0 mol NO2 16.0 mol NO2 32.0 mol NO2

If you have equal concentrations of the following aqueous solutions, which will have the highest conductivity? CaCl2 KBr Na2SO4 Al(NO3)3 LiC2H3O2

If you have equal concentrations of the following aqueous solutions, which will have the highest conductivity? CaCl2 KBr Na2SO4 Al(NO3)3 LiC2H3O2

Which mixture will produce a precipitate? NH 3 + HF HClO 4 + KOH Na 2 SO + PbCl Ca(NO ) + KC H O (NH CO + Na PO

Which mixture will produce a precipitate? NH 3 + HF HClO 4 + KOH Na 2 SO + PbCl Ca(NO ) + KC H O (NH CO + Na PO

What is(are) the spectator ion(s) in the following reaction? KOH (aq) + HF (aq) KF (aq) + H2O (l) K+ F- K+ and F- OH- and H+ OH-

What is(are) the spectator ion(s) in the following reaction? KOH (aq) + HF (aq) KF (aq) + H2O (l) K+ F- K+ and F- OH- and H+ OH-

Which of the following reactions has the net ionic equation: H+ (aq) + OH- (aq) H2O (l) Reaction 1 Reactions 1, 4 Reactions 2, 3 Reactions 2, 4 Reactions 3, 4

Which of the following reactions has the net ionic equation: H+ (aq) + OH- (aq) H2O (l) Reaction 1 Reactions 1, 4 Reactions 2, 3 Reactions 2, 4 Reactions 3, 4

Which will have the highest concentration of Na+? 0.35 M Na2SO4 0.40 M Na3PO4 0.50 M NaNO3 0.80 M NaOH 1.00 M NaCl

Which will have the highest concentration of Na+? 0.35 M Na2SO4 0.40 M Na3PO4 0.50 M NaNO3 0.80 M NaOH 1.00 M NaCl

Given the following reactions, rank the activity of each metal. Mg>Al>Zn>Cu Al>Mg>Zn>Cu Cu>Zn>Al>Mg Zn>Cu>Al>Mg Al>Mg>Cu>Zn

Given the following reactions, rank the activity of each metal. Mg>Al>Zn>Cu Al>Mg>Zn>Cu Cu>Zn>Al>Mg Zn>Cu>Al>Mg Al>Mg>Cu>Zn

Which of the following substances would be considered a nonelectrolyte? Methanol, CH3OH Hydrofluoric acid, HF Sulfuric acid, H2SO4 Sodium hydroxide, NaOH

Correct Answer: Methanol, CH3OH Hydrofluoric acid, HF Sulfuric acid, H2SO4 Sodium hydroxide, NaOH Methanol is an organic molecule that does not form ions in solution.

Which ions are spectator ions in the reaction represented by the following molecular equation? AgNO3(aq) + NaCl(aq)  AgCl(s) + NaNO3(aq) Na+ and NO3 Na+ and Cl Ag+ and Cl Ag+ and NO3

Correct Answer: Na+ and NO3 Na+ and Cl Ag+ and Cl Ag+ and NO3 Spectator ions are present, but play no direct role in the reaction.

Which of the following is not an oxidation-reduction reaction? CH4(g) + 2 O2(g)  CO2(g) + 2 H2O(g) HCl(aq) + Zn(s)  ZnCl2(aq) + H2(g) Ca(OH)2(aq) + 2 HCl(aq)  CaCl2(aq) + 2 H2O(l) Fe2O3(s) + 3 H2(g)  2 Fe(s) + 3 H2O(l)

Correct Answer: CH4(g) + 2 O2(g)  CO2(g) + 2 H2O(g) HCl(aq) + Zn(s)  ZnCl2(aq) + H2(g) Ca(OH)2(aq) + 2 HCl(aq)  CaCl2(aq) + 2 H2O(l) Fe2O3(s) + 3 H2(g)  2 Fe(s) + 3 H2O(l) This is an acid-base reaction, and no species change oxidation state.

What is the oxidation state of sulfur in the compound SF2? +2 +4 2 4

Correct Answer: +2 +4 2 4 Because F is 1, and there are two F atoms, S must be +2.

What is the oxidation state of nitrogen in the compound N2O5? +1 +2 +5 3

Correct Answer: +1 +2 +5 3 Because O is 2, and there are five O atoms, each of the two N atoms must be +5.

Which of the following compounds contains a chlorine atom with an oxidation number of +5? ClF5 KClO4 HCl Cl2

Correct Answer: ClF5 KClO4 HCl Cl2 Because F is 1, and there are five F atoms, the Cl atom must be +5. Structure of ClF5 is to the left.

A 80.0 mL solution of sodium chloride at 1.00 M is to be diluted to 0.100 M. What is the total volume of the diluted solution? 0.0720 L 0.720 L 0.0800 L 0.800 L MdiluteVdilute = moles = MconcVconc

Correct Answer: 0.0720 L 0.720 L 0.0800 L 0.800 L 0.100 M(Vdilute) = (1.00 M)(80.0 mL) Vdilute = (1.00 M)(80.0 mL)/0.100 M Vdilute = 800. mL, or 0.800 L

How many moles of phosphoric acid, H3PO4, are needed to prepare 2 How many moles of phosphoric acid, H3PO4, are needed to prepare 2.00 L of a 0.75 M phosphoric acid solution? 4.0 moles 1.5 moles 1.8 moles 0.75 moles

How many moles of phosphoric acid, H3PO4, are needed to prepare 2 How many moles of phosphoric acid, H3PO4, are needed to prepare 2.00 L of a 0.75 M phosphoric acid solution? 4.0 moles 1.5 moles 1.8 moles 0.75 moles

A 50.0 mL solution of HCl at 1.00 M is to be titrated with a solution of 2.50 M NaOH. How many mL of NaOH are required to reach the equivalence point? 20.0 mL 125 mL 50.0 mL 70.0 mL

0.0500 mol acid(1 mol base/1 mol acid) Correct Answer: 20.0 mL 125 mL 50.0 mL 70.0 mL (50.0 mL HCl)(1.00 M) = 0.0500 mol acid 0.0500 mol acid(1 mol base/1 mol acid) = 0.100 mol base Vbase = mol/M = 0.100 mol/2.50M = 0.0200 L or 20.0 mL

A 50.0 mL solution of H2SO4 at 1.00 M is to be titrated with a solution of 0.500 M NaOH. How many mL of NaOH are required to reach the equivalence point? 100. mL 200. mL 300. mL 50.0 mL

0.0500 mol acid(2 mol base/1 mol acid) Correct Answer: 100. mL 200. mL 300. mL 50.0 mL (50.0 mL H2SO4)(1.00 M) = 0.0500 mol acid 0.0500 mol acid(2 mol base/1 mol acid) = 0.100 mol base Vbase = mol/M = 0.100 mol/0.500M = 0.200 L or 200. mL

KCN(aq) K+(aq) and CN–(aq) K–(aq) and CN+(aq) K+(aq), C4–(aq), and N3+(aq)

KCN(aq) K+(aq) and CN–(aq) K–(aq) and CN+(aq) K+(aq), C4–(aq), and N3+(aq)

NaClO4(aq) Na+(aq) and 4ClO–(aq) Na+(aq), Cl–(aq) and 4O2–(aq) Na+(aq) and ClO4–(aq)

NaClO4(aq) Na+(aq) and 4ClO–(aq) Na+(aq), Cl–(aq) and 4O2–(aq) Na+(aq) and ClO4–(aq)

Cannot determine without concentration information. Both will cause the lightbulb to glow with equal brightness. MgBr2 CH3OH

Cannot determine without concentration information. Both will cause the lightbulb to glow with equal brightness. MgBr2 CH3OH

Cannot determine without concentration information. HBr H2SO3 HC2H3O2

Cannot determine without concentration information. HBr H2SO3 HC2H3O2

Concentration (molarity) remains the same. The new concentration is 0.25 M. The new concentration is 1.00 M. The new concentration is 2.00 M.

Concentration (molarity) remains the same. The new concentration is 0.25 M. The new concentration is 1.00 M. The new concentration is 2.00 M.

12.50 mL 25.00 mL 50.00 mL 75.00 mL

12.50 mL 25.00 mL 50.00 mL 75.00 mL