Chemistry Test 3
When the bonds formed in a chemical reaction are weaker and less stable than those broken, the products have
__greater____ POTENTIAL energy than the reactants.
Because spectator ions are not involved in the reaction, they are often
left out of the chemical equation.
In solutions of solids dissolved in liquids, we call the solid the ____ and the liquid the ________.
solid = solute liquid = solvent ex: water
Sometimes a double-displacement reaction has one product that is insoluble in water. As that product forms, it emerges, or precipitates, from the solution as a solid. This process is called precipitation, such a reaction is called a precipitation reaction, and the solid is called the precipitate.
process: precipitation solid= precipitate
Balance HF + CCl4 → CCl2F2 + CCl3F + HCl
3 HF + 2 CCl4 → CCl2F2 + CCl3F + 3 HCl
Industrial chemists make hydrofluoric acid (which is used in aluminum and uranium processing, to etch glass, and to make CFCs) from the reactions of aqueous calcium fluoride and aqueous sulfuric acid. Write the complete equation for this reaction. (Use the lowest possible coefficients. Include states-of-matter in your answer.) hydrofluoric acid = HF calcium fluoride = CaF2 sulfuric acid = H2SO4 *SAYS INCLUDE STATES OF MATTER IN ANSWER
H2SO4(aq) + CaF2(aq) → 2 HF(aq) + CaSO4(s)
Magnesium sulfate, a substance used for fireproofing and paper sizing, is made in industry from the reaction of aqueous sulfuric acid and solid magnesium hydroxide. Write the complete equation for this reaction.
H2SO4(aq) + Mg(OH)2(s) --> 2H2O(l) + MgSO4(aq)
Identify the amphoteric substance in the following equations. (Omit states-of-matter from your answer.) HCl(aq) + HS-(aq) → Cl-(aq) + H2S(aq) HS-(aq) + OH-(aq) → S2-(aq) + H2O(l)
In the Brønsted-Lowry theory, an amphoteric substance can act as both a Brønsted-Lowry acid and a Brønsted-Lowry base. --> The one substance that meets this definition is HS−.
Naming Monotomic Ions
Ions in: * Group 1A end up with a +1 charge * Group 2A: +2 charge * Group 3A: +3 charge Write the name for each of these monatomic ions. (Hint: Remember to include the word "ion" in the name of ionic substances.) 1) P^3- =Phosphide ion 2) Li^+ = Lithium ion 3) Sc^3+ = Scandium ion
When the bonds in the product are more stable than those in the reactants, we say they are stronger than the bonds in the reactants. The product therefore has _______ potential energy, and energy is released overall.
LOWER Potential Energy
Potassium hydroxide has many uses, including the manufacture of soap. It is made by running an electric current through a water solution of potassium chloride. Both potassium chloride and water are reactants, and the products are potassium hydroxide, hydrogen, and chlorine. Write a balanced equation, without including states, for this reaction. (Use the lowest possible whole number coefficients.)
STEP 1: H2O + KCl = KOH + Cl2 + H2 ANSWER: 2 H2O + 2 KCl = 2 KOH + Cl2 + H2
Classify each of the following changes as exothermic or endothermic.
When heat is transferred to the surroundings the change is exothermic. When heat is transferred to the system the change is endothermic. (a) Leaves decaying in a compost heap is exothermic because heat is produced by the decomposition of organic matter. (b) Wood burning in an old-style stove is exothermic because heat is produced by the oxidation of the wood. (c) Liquid nitrogen evaporating is endothermic because heat is required to convert a liquid into a gas.
Describe the process for dissolving the ionic compound lithium iodide, LiI, in water, including the nature of the particles in solution and the attractions between the particles in the solution.
When solid lithium iodide is added to water, all of the ions at the surface of the solid can be viewed as shifting back and forth between moving out into the water and returning to the solid surface. Sometimes when an ion moves out into the water, a water molecule collides with it, helping to break the ionic bond, and pushing it out into the solution. Water molecules move into the gap between the ion in solution and the solid and shield the ion from the attraction to the solid. The ions are kept stable and held in solution by attractions between them and the polar water molecules. The negatively charged oxygen ends of water molecules surround the lithium ions, and the positively charged hydrogen ends of water molecules surround the iodide ions.
For each of the following equations, identify the Brønsted-Lowry acid and base for the forward reaction. (Omit states-of-matter from your answer.)
a) 3 NaOH(aq) + H3PO4(aq) 3 H2O(l) + Na3PO4(aq) Base= NaOH Acid= H3PO4 b) HS-(aq) + HIO3(aq) H2S(aq) + IO3-(aq) Base= HS- Acid= HIO3 c) HS-(aq) + OH-(aq) S2-(aq) + H2O(l) Base = OH- Acid = HS-
For each of the following equations, determine the oxidation number for each atom in the equation and identify whether the reaction is a redox reaction or not. If the reaction is redox, identify what is oxidized, what is reduced, the oxidizing agent, and the reducing agent. (Enter your answer using the format +1 and -2. Enter NONE in any unused answer blanks.)
a) CaO(s) + H2O(l) → Ca2+(aq) + 2OH-(aq) (a) None of the substances in this equation change oxidation states. Therefore: This is not a redox reaction. The substance oxidized is none. The substance reduced is none. The oxidizing agent is none. The reducing agent is none. b) 2 Cr(s) + 3 CuSO4(aq) → Cr2(SO4)3(aq) + 3 Cu(s) (b) Both Cr and Cu change oxidation states in this equation. Therefore: This is a redox reaction. The substance oxidized is Cr. The substance reduced is Cu. The oxidizing agent is CuSO4. The reducing agent is Cr. c) 3 H2SO3(aq) + 2 HNO3(aq) → 2 NO(g) + H2O(l) + 3 H2SO4(aq) -redox -s oxidized, n reduced, HNO3 ox agent, H2SO3 red agent
Write the complete equation for the neutralization reactions that take place when the following water solutions are mixed. (If an acid has more than one acidic hydrogen, assume that there is enough base to remove all of them. Assume that there is enough acid to neutralize all of the basic hydroxide ions. Use the lowest possible coefficients. Include states-of-matter in your answer.)
a) H2SO4(aq) + NaOH(aq) answer: H2SO4(aq) + 2 NaOH(aq) → Na2SO4(aq) + 2 H2O(l) b) KOH(aq) + HF(aq) answer: HF(aq) + KOH(aq) → KF(aq) + H2O(l) c) Cd(OH)2(s) + HCl(aq) answer: 2 HCl(aq) + Cd(OH)2(s) → CdCl2(aq) + 2 H2O(l) d) HCl(aq) + LiOH(aq) answer: HCl(aq) + LiOH(aq) --> LiCl(aq) + H2O(l) e) HCl(aq) + LiOH(aq) answer: HCl(aq) + LiOH(aq) → LiCl(aq) + H2O(l) f) H2SO4(aq) + NaOH(aq) answer: H2SO4(aq) + 2 NaOH(aq) → Na2SO4(aq) + 2 H2O(l) g) KOH(aq) + HF(aq) answer: HF(aq) + KOH(aq) → KF(aq) + H2O(l) Answer after arrow! * ___ LiOH(aq) + ___ HNO3(aq) --> LiNO3 + H2O *___ Co(OH)2(s) + _2__ HNO3(aq) --> Co(NO3)2 + 2 H2O *___ H3PO4(aq) + _3__ KOH(aq) __. 3 H2O + K3PO4
Write the formula for the conjugate acid of each of the following. (Omit states-of-matter from your answer.)
a) IO3^- answer: HIO3 b) PO3^3- answer: HPO3^2- c) HSO3^- answer: HSO3^- d) H^- answer: H2 e) HC2O^4- = H2C2O4. f) BrO^- = HBrO. g) SO3^2- = HSO3−. h)NH2^- = NH3
For each of the following pairs of formulas, predict whether the substances they represent would react to yield a precipitate. (The products formed in the reactions that take place are used to coat steel, as a fire-proofing filler for plastics, in cosmetics, and as a topical antiseptic.) If there is no reaction, write, "NONE". If there is a reaction, write the complete equation for the reaction. (Use the lowest possible whole number coefficients. Include states-of-matter in your answer.)
a) NaCl(aq) + Al(NO3)3(aq) answer: NONE b) Ni(NO3)2(aq) + NaOH(aq) answer: Ni(NO3)2(aq) + 2 NaOH(aq) → Ni(OH)2(s) + 2 NaNO3(aq) c) Zn(C2H3O2)2(aq) + Na2CO3(aq) answer: Zn(C2H3O2)2(aq) + Na2CO3(aq) → ZnCO3(s) + 2 NaC2H3O2(aq) d) MnCl2(aq) + Na3PO4(aq) answer: 3MnCl2(aq) + 2Na3PO4(aq) --> Mn3(PO4)2(s) + 6NaCl(aq)
For each of the following pairs of formulas, predict whether the substances they represent would react in a precipitation reaction. If there is no reaction, write, "NONE". If there is a reaction, write the complete equation for the reaction. (Use the lowest possible whole number coefficients. Include states-of-matter in your answer.)
a) NaCl(aq) + Pb(NO3)2(aq) answer: 2NaCl(aq) + Pb(NO3)2(aq) --> 2NaNO3(aq) + PbCl2(s) b) NaOH(aq) + Zn(NO3)2(aq) answer: 2NaOH(aq) + Zn(NO3)2(aq)--> 2NaNO3(aq) + Zn(OH)2(s) c) Pb(C2H3O2)2(aq) + Na2SO4(aq) answer: Pb(C2H3O2)2(aq) + Na2SO4(aq) --> PbSO4(s) + 2NaC2H3O2(aq) d) NH4Cl(aq) + CaSO3(aq) answer: NONE
Complete the following equations by writing the formulas for the acid and base that could form the given products. (Enter a complete balanced equation. Use the lowest possible coefficients. Include states-of-matter in your answer.)
a) _____ + _____ → H2O(l) + NaCl(aq) answer: HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) b) _____ + _____ → 2 H2O(l) + Li2SO4(aq) answer: H2SO4(aq) + 2 LiOH(aq) → Li2SO4(aq) + 2 H2O(l) c) _____ + _____ → H2O(l) + CO2(g) + 2 KCl(aq) answer: 2 HCl(aq) + K2CO3(aq) → 2 KCl(aq) + H2O(l) + CO2(g)
Describe the information given in the following chemical equation. 2 NaCl(l) --> 2 Na(l) + Cl2(g) above arrow = electric current
empty box: synthesis reaction
Iron(III) sulfate is made in industry by the neutralization reaction between solid iron(III) hydroxide and aqueous sulfuric acid. The iron(III) sulfate is then added with sodium hydroxide to municipal water in water treatment plants. These compounds react to form a precipitate that settles to the bottom of the holding tank, taking impurities with it. Write the complete equations for both the neutralization reaction that forms iron(III) sulfate and the precipitation reaction between water solutions of iron(III) sulfate and sodium hydroxide. (Obj 11)
neutralization reaction: 2Fe(OH)3(s) + 3H2SO4(aq) --> Fe2(SO4)3(aq) + 6H2O(l) precipitation reaction: Fe2(SO4)3(aq) + 6NaOH(aq) --> 2Fe(OH)3(s) + 3Na2SO4(aq)
