1. A solution of hydrochloric acid can be standardized by reacting it with a know quantity of sodium carbonate. If 0.851 g of Na2CO3 required 41.36 mL of HCl solution to completely react in a titration, what is the concentration of the HCl solution? Na2CO3(aq) + 2 HCl(aq) -> 2 NaCl(aq) + CO2(g) + H2O(l) 2. If 20.00 mL of an unknown HCl solution were titrated with 32.30 mL of 0.323 M NaOH solution to a faint pink phenolphthalein endpoint, what is the concentration of the HCl solution? 3. A box of borax laundry booster claims to be more than 98% pure. If a sample of borax with a mass of 2.272 g was neutralized by 26.28 mL of 0.444 M HCl in a titration, is the borax as pure as the manufacturer claims? The formula of borax is Na2B4O7 · 10H2O, and its formula mass is 381.37 g/mol. Na2B4O7 · 10H2O(aq) + 2 HCl(aq) -> 4 B(OH)3(aq) + 5 H2O(l) + 2 NaCl(aq)
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For the first question, we need to find the molar mass of Na2CO3, which is approximately 105.99 g/mol. The number of moles of Na2CO3 is then 0.851 g / 105.99 g/mol = 0.00802 mol. According to the balanced chemical equation, the molar ratio of Na2CO3 to HCl is 1:2, Show more…
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Solution of hydrochloric acid can be standardized by reacting it with a known quantity of sodium carbonate. If 0.85 g of Na2CO3 required 41.36 mL of HCl solution to completely react in titration, what is the concentration of the HCl solution? Na2CO3(aq) + 2HCl(aq) -> 2NaCl(aq) + CO2(g) + H2O(l)
Adi S.
A 28.3 mL hydrochloric acid solution was standardized using 0.256 g of sodium carbonate. (Na2CO3 = 106 g/mol; HCl = 36.46 g/mol) Na2CO3 + 2 HCl → 2 NaCl + H2CO3 1. How many millimoles of sodium carbonate was used in the titration? A. 0.00242 B. 0.00702 C. 0.344 D. 54.3 2. What is the reaction ratio of this titration? A. 1 mole acid to 1 mole base B. 1 mole acid to 2 moles base C. 2 moles acid to 1 mole base D. 1 mole acid to 3 moles base 3. How many millimoles of hydrochloric acid was used in the titration? A. 0.00121 B. 0.00351 C. 0.00483 D. 0.0140 4. What is the mass of hydrochloric acid in grams? A. 0.0881 B. 0.176 C. 0.372 D. 1.49 5. What is the concentration of hydrochloric acid in %w/v? A. 0.311 B. 0.622 C. 1.31 D. 5.26
About half of the hydrochloric acid produced annually in the United States ( $3.0$ billion pounds) is used in metal pickling. This process involves the removal of metal oxide layers from metal surfaces to prepare them for coating. (a) Write the overall and net ionic equations for the reaction between iron(III) oxide, which represents the rust layer over iron, and $\mathrm{HCl}$. Identify the Broønsted acid and base. (b) Hydrochloric acid is also used to remove scale (which is mostly $\mathrm{CaCO}_{3}$ ) from water pipes (see p. 129). Hydrochloric acid reacts with calcium carbonate in two stages; the first stage forms the bicarbonate ion, which then reacts further to form carbon dioxide. Write equations for these two stages and for the overall reaction. (c) Hydrochloric acid is used to recover oil from the ground. It dissolves rocks (often $\mathrm{CaCO}_{3}$ ) so that the oil can flow more easily. In one process, a 15 percent (by mass) HCl solution is injected into an oil well to dissolve the rocks. If the density of the acid solution is $1.073 \mathrm{~g} / \mathrm{mL}$, what is the $\mathrm{pH}$ of the solution?
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