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Chapter 3: Problem 23

Determine the formula weights of each of the following compounds: (a) nitric acid, HNO \(_{3} ;\) (b) \(\mathrm{KMnO}_{4} ;\) (c) \(\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}\) (d) quartz, SiO \(_{2} ;\) (e) gallium sulfide, (f) chromium(III) sulfate, (g) phosphorus trichloride.

Short Answer

Expert verified
The formula weights of the given compounds are as follows: (a) HNO₃: 63.02 g/mol, (b) KMnO₄: 158.04 g/mol, (c) Ca₃(PO₄)₂: 310.18 g/mol, (d) SiO₂: 60.09 g/mol, (e) Ga₂S₃: 235.65 g/mol, (f) Cr₂(SO₄)₃: 392.21 g/mol, and (g) PCl₃: 137.32 g/mol.

Step by step solution

01

Nitric Acid (HNO₃)

First, find the molecular weights of H, N, and O from the periodic table: H = 1.01, N = 14.01, O = 16.00. Now, calculate the formula weight for HNO₃: 1(1.01) + 1(14.01) + 3(16.00) = 1.01 + 14.01 + 48.00 = 63.02 g/mol.
02

Potassium Permanganate (KMnO₄)

Find the molecular weights of K, Mn, and O from the periodic table: K = 39.10, Mn = 54.94, O = 16.00. Now, calculate the formula weight for KMnO₄: 1(39.10) + 1(54.94) + 4(16.00) = 39.10 + 54.94 + 64.00 = 158.04 g/mol.
03

Calcium Phosphate (Ca₃(PO₄)₂)

Find the molecular weights of Ca, P, and O from the periodic table: Ca = 40.08, P = 30.97, O = 16.00. Now, calculate the formula weight for Ca₃(PO₄)₂: 3(40.08) + 2(1(30.97) + 4(16.00)) = 120.24 + 2(30.97 + 64.00) = 120.24 + 2(94.97) = 120.24 + 189.94 = 310.18 g/mol.
04

Quartz (SiO₂)

Find the molecular weights of Si and O from the periodic table: Si = 28.09, O = 16.00. Now, calculate the formula weight for SiO₂: 1(28.09) + 2(16.00) = 28.09 + 32.00 = 60.09 g/mol.
05

Gallium Sulfide (Ga₂S₃)

Find the molecular weights of Ga and S from the periodic table: Ga = 69.72, S = 32.07. Now, calculate the formula weight for Ga₂S₃: 2(69.72) + 3(32.07) = 139.44 + 96.21 = 235.65 g/mol.
06

Chromium(III) Sulfate (Cr₂(SO₄)₃)

Find the molecular weights of Cr, S, and O from the periodic table: Cr = 52.00, S = 32.07, O = 16.00. Now, calculate the formula weight for Cr₂(SO₄)₃: 2(52.00) + 3(1(32.07) + 4(16.00)) = 104.00 + 3(32.07+64.00) = 104.00 + 3(96.07) = 104.00 + 288.21 = 392.21 g/mol.
07

Phosphorus Trichloride (PCl₃)

Find the molecular weights of P and Cl from the periodic table: P = 30.97, Cl = 35.45. Now, calculate the formula weight for PCl₃: 1(30.97) + 3(35.45) = 30.97 + 106.35 = 137.32 g/mol. In conclusion, we have calculated the formula weights for all the given compounds: - Nitric Acid (HNO₃): 63.02 g/mol - Potassium Permanganate (KMnO₄): 158.04 g/mol - Calcium Phosphate (Ca₃(PO₄)₂): 310.18 g/mol - Quartz (SiO₂): 60.09 g/mol - Gallium Sulfide (Ga₂S₃): 235.65 g/mol - Chromium(III) Sulfate (Cr₂(SO₄)₃): 392.21 g/mol - Phosphorus Trichloride (PCl₃): 137.32 g/mol

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Most popular questions from this chapter

Serotonin is a compound that conducts nerve impulses in the brain. It contains \(68.2 \% \mathrm{C}, 6.86 \% \mathrm{H}, 15.9 \% \mathrm{N},\) and 9.08\(\% \mathrm{O}\) . Its molar mass is 176 \(\mathrm{g} / \mathrm{mol} .\) Determine its molecular formula.

(a) Combustion analysis of toluene, a common organic solvent, gives 5.86 \(\mathrm{mg}\) of \(\mathrm{CO}_{2}\) and 1.37 \(\mathrm{mg}\) of \(\mathrm{H}_{2} \mathrm{O}\) . If the compound contains only carbon and hydrogen, what is its empirical formula? (b) Menthol, the substance can smell in mentholated cough drops, is composed of \(\mathrm{C}, \mathrm{H},\) and \(\mathrm{O} . \mathrm{A}\) 0.1005 -gsample of mentholis combusted, producing 0.2829 \(\mathrm{g}\) of \(\mathrm{CO}_{2}\) and 0.1159 \(\mathrm{g}\) of \(\mathrm{H}_{2} \mathrm{O} .\) What is the empirical formula for menthol? If menthol has a molar mass of 156 \(\mathrm{g} / \mathrm{mol}\) what is its molecular formula?

A mixture containing \(\mathrm{KClO}_{3}, \mathrm{K}_{2} \mathrm{CO}_{3}, \mathrm{KHCO}_{3},\) and \(\mathrm{KCl}\) was heated, producing \(\mathrm{CO}_{2}, \mathrm{O}_{2},\) and \(\mathrm{H}_{2} \mathrm{O}\) gases according to the following equations: $$ \begin{array}{l}{2 \mathrm{KClO}_{3}(s) \longrightarrow 2 \mathrm{KCl}(s)+3 \mathrm{O}_{2}(g)} \\ {2 \mathrm{KHCO}_{3}(s) \longrightarrow \mathrm{K}_{2} \mathrm{O}(s)+\mathrm{H}_{2} \mathrm{O}(g)+2 \mathrm{CO}_{2}(g)} \\\ {\mathrm{K}_{2} \mathrm{CO}_{3}(s) \longrightarrow \mathrm{K}_{2} \mathrm{O}(s)+\mathrm{CO}_{2}(g)}\end{array} $$ The KCl does not react under the conditions of the reaction. If 100.0 g of the mixture produces 1.80 \(\mathrm{g}\) of \(\mathrm{H}_{2} \mathrm{O}, 13.20 \mathrm{g}\) of \(\mathrm{CO}_{2}\) and 4.00 \(\mathrm{g}\) of \(\mathrm{O}_{2},\) what was the composition of the original mixture? (Assume complete decomposition of the mixture.)

Sodium hydroxide reacts with carbon dioxide as follows: $$ 2 \mathrm{NaOH}(s)+\mathrm{CO}_{2}(g) \longrightarrow \mathrm{Na}_{2} \mathrm{CO}_{3}(s)+\mathrm{H}_{2} \mathrm{O}(l) $$ Which is the limiting reactant when 1.85 mol \(\mathrm{NaOH}\) and 1.00 \(\mathrm{mol} \mathrm{CO}_{2}\) are allowed to react? How many moles of \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) can be produced? How many moles of the excess reactant remain after the completion of the reaction?

The fizz produced when an Alka-Seltzer tablet is dissolved in water is due to the reaction between sodium bicarbonate \(\left(\mathrm{NaHCO}_{3}\right)\) and citric acid \(\left(\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}\right) :\) $$ \begin{aligned} 3 \mathrm{NaHCO}_{3}(a q)+\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(a q) & \longrightarrow \\ & 3 \mathrm{CO}_{2}(g)+3 \mathrm{H}_{2} \mathrm{O}(l)+\mathrm{Na}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(a q) \end{aligned} $$ In a certain experiment 1.00 g of sodium bicarbonate and 1.00 g of citric acid are allowed to react. (a) Which is the limiting reactant? (b) How many grams of carbon dioxide form? (c) How many grams of the excess reactant remain after the limiting reactant is completely consumed?
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