3.12 Balance the following equations. 6 point

(a)____CaC₂(s) + ___H₂O(ℓ) ®___Ca(OH)₂(s) + ___C₂H₂(g)

(b)___(NH₄)₂Cr₂O₇(s) ®___Cr₂O₃(s) + ___N₂(g) + ____H₂O(g)

(c) ___CH₃NH₂(g) + ___O₂(g) ® ____CO₂(g) + ___N₂(g) + ____ H₂O(g)

3.16 Balance the following equations. 6 point

(a) reaction to produce “superphosphate” fertilizer:

_____Ca₃(PO₄)₂(s) + ____H₂SO₄(aq) ®____Ca(H₂PO₄)₂(aq) + ___CaSO₄(s)

(b) reaction to produce diborane, B₂H₆:

___NaBH₄(s)+ ____H₂SO₄ (aq)® ___B₂H₆(g) + H₂(g) + ____Na₂SO₄(aq)

(c) reaction to produce tungsten metal from tungsten(VI)oxide:

____WO₃(s)+ ____H₂(g)®___W(s)+ ___H₂O()

(d) decomposition of ammonium dichromate:

____(NH₄)₂Cr₂O₇(s) ®____N₂(g)+ ___H₂O(ℓ) + ___ Cr₂O₃(s)

3.22 When a substance dissolves, does a chemical reaction always occur? If not, what does happen? 6 point

3.26 Classify the following compounds as electrolytes or non-electrolytes. 6 point

(a) potassium chloride, KCl, (b)hydrogen peroxide, H₂O₂, (c) methane, CH₄,

(d) barium nitrate, Ba(NO₃)₂.

3.28 Decide whether each of the following is water-soluble. If soluble, tell what ions are produced. (a) Na₂CO₃,(b) CuSO₄, (c) NiS, (d) BaBr₂ 6 point

3.34 Balance the following equations and then write the net ionic equations. 6 point

(a)(NH₄)₂CO₃(aq) + Cu(NO₃)₂(aq)® CuCO₃(s) + NH₄NO₃(aq)

(b)Pb(OH)₂(s) + HCl(aq)®PbCl₂(s) + H₂O()

(c)BaCO₃(s) + HCl(aq) ® BaCl₂(aq)+ H₂O() + CO₂(g)

3.38 How many entities are present in each of the following? 8 point

(a)3.21 mol argon atoms

(b) 1.3 ´10^–12mol marbles

(c)3 ´10⁶mol water molecules

(d)7.63 ´10^–18mol basketballs

3.42 Calculate the molar masses (in grams per mole) of each of the following. (a) cane sugar, C₁₂H₂₂O₁₁, (b) laughing gas, N₂O, and (c) vitamin A, C₂₀H₃₀O. 6 point

3.50 Calculate the mass in grams of 13.5 mol of (a) vinyl chloride, C₂H₃Cl, the starting material for a plastic, (b) capsaicin, C₁₈H₂₇NO₃, the substance that makes red chili peppers “hot,” and (c) stearic acid, C₁₈H₃₆O₂, used in soaps.

8 point

3.56 A sample of H₂C₂O₄2H₂O of mass 3.35 g is heated to drive off the waters of hydration (designated separately in the chemical formula). What mass of H₂C₂O₄remains once the water has been removed by heating? 8 point

3.60 Determine the simplest formulas of the following compounds: (a) the food enhancer monosodium glutamate (MSG), which has the composition 35.51% C, 4.77% H, 37.85% O, 8.29% N, and 13.60% Na, (b) zircon, a diamond-like mineral, which has the composition 34.91% O, 15.32% Si, and 49.76% Zr,

(c) nicotine, which has the composition 74.0% C, 8.65% H, and 17.4% N.

8 point

3.64 What is the molarity of each ion present in aqueous solutions prepared by dissolving 20.00 g of the following compounds in water to make 4.50 L of solution? (a) cobalt(III)chloride, (b) nickel(III) sulfate, (c)sodium permanganate, (d) iron(II) bromide 8 point

3.66 How many grams of solute are present in each of these solutions? 8 point

(a)37.2 mL of 0.471 M HBr

(b)113.0 L of 1.43 M Na₂CO₃

(c)21.2 mL of 6.8 M CH₃COOH

(d) 1.3 ´10^-4L of 1.03 M H₂SO₃

3.68 Determine the initial volume (in mL) needed to generate the desired solutions by dilution. 10 point

(a)10.0 L of 0.45 M solution from 3.0 M solution,

(b)1.50 L of 1.00 M solution from 11.7 M solution,

(c)100.0 mL of 0.025 M solution from 1.15 M solution,

(d)50.0 mL of 3.3 ´10^–4M solution from 0.25 M solution