Al(s) + HCl(aq) AlCl3(aq) + H2(g)
Zn(s) + HCl(aq) ZnCl2(aq) + H2(g)
1) Consider the unbalanced equations above. A 0.250 g sample of a mixture of aluminum and zinc metal is reacted with an excess of hydrochloric acid. Both metals react with hydrochloric acid. The sample produces 210.2 mL of hydrogen gas at STP.
(a) What is the mass percent aluminum in the sample?
(b) What is the mass percent zinc in the sample?
2)Bi(NO3)5(aq) + Na2S(aq) Bi2S5(s) + NaNO3(aq)
Consider the unbalanced equation above. A 22.5 g sample of impure Bi(NO3)5 reacts with excess Na2S. If the sample produces 9.00 g of Bi2S5,what is the mass percent of Bi(NO3)5 in the sample?
3)CaH2(s) + H2O(l) Ca(OH)2(s) + H2(g)
Consider the unbalanced equation above. What is the maxiumum volume of H2 gas at STP that can be produced when 29.0 g of CaH2 and 10.5 g H2O react?
3) CS2(g) + O2(g) CO2(g) + SO2(g)
(a) Consider the unbalanced equation above. What is the maximum mass of SO2 that can be produced when 47.5 g of CS2 and 38.5 g O2 react?
(b) Assume the reaction in part (a) goes to completion. Calculate the mass of excess reactant.
4)What is the final volume of 10.5 L of carbon dioxide gas at 20.2°C if the gas is heated to 94.5°C? Assume the pressure and the amount of gas are held constant.
5)What is the final pressure in the container if 12.0 L of helium gas at 810. mm Hg is expanded to 30.0 L? Assume the temperature and the amount of gas are held constant.
Consider the unbalanced equations above. A 0.250 g sample of a mixture of aluminum and zinc metal is reacted w?
2013-04-27 11:46 pm
回答 (2)
2013-04-28 9:43 pm
✔ 最佳答案
2)2 Bi(NO3)5 + 5 Na2S → Bi2S5 + 10 NaNO3
(9.00 g Bi2S5) / (578.2883 g Bi2S5/mol) x (2 mol Bi(NO3)5 / 1 mol Bi2S5) x
(519.0055 g Bi(NO3)5/mol) / (22.5 g) = 0.718 = 71.8% Bi(NO3)5 by mass
4)
(10.5 L) x (94.5 + 273.15 K) / (20.2 + 273.15 K) = 13.2 L
5)
(810 mmHg) x (12.0 L / 30.0 L) = 324 mmHg
2016-08-07 2:29 pm
* First, we discover the mole of zinc: mole = mass / molecular mass mole = 21 / 65 mole = 0.323 Then we discover how many moles of hydrogen do 0.323 mole of Zinc gives: 1 mole of zinc ----->1 mole of hydrogen zero.323 mole of zinc -----> x mole of hydrogen move multiplying we get 0.323 mole next we discover mass of zero.323 mole hydrogen: Mass = Mole x Molecular mass Mass = zero.323 x 2 Mass = zero.646 grams ************************* reducing agent is the substance that undergoes oxidation: Zn is oxidized right here due to the fact that, Zinc losses electron to become zinc ions (ZnCl₂). It can be oxidation number raises from 0 to +1. So zinc is the reducing agent. ************************** Oxidizing agent is the substance that undergoes reduction: H+ ions are diminished here when you consider that it features electrons to end up hydrogen molecules (H₂), it's oxidation quantity also decreases from +1 to zero. So H+ ions within the acid is the oxidizing agent.
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