SECTION GNMENT . A hydrochloric acid solution is standardized using 0.500 g of s

Question

SECTION GNMENT . A hydrochloric acid solution is standardized using 0.500 g of sodium carbonate, NazCO3 nd the molarity of the acid if 29.50 mL are required to reach a phenolphthalein endpoint. 2 HCI(aq) NaCOs (s)2 NaCI(ag) HO)CO2(8) A 10.0-mL sample of household ammonia solution required 18.15 mL of 0.320 M HCl to reach neutralization. Calculate (a) the molar concentration of the ammonia and (b) the mass/mas percent concentration of ammonia (17.04 g/mol), given a solution density of 0.990g/mL HCl (aq) + NH3 (aq) NH4Cl (aq) ? If 22.15 mL of 0.100 M sulfuric acid is required to neutralize 10.0 mL of lithium hydroxide solution, what is the molar concentration of the base? H2SO4 (aq) + 2LiOH(aq) Li2SO4 (aq) 2H20(1) +

Explanation / Answer

Question 1

Balanced equation:
2 HCl + Na2CO3 ====> 2 NaCl + H2O + CO2

0.5 gm of Na2CO3 = 0.5 / 105.988 =  0.004717 Moles

Moles of HCl required to neutralize = 0.009434 Moles

Molarity of HCl =  0.009434 x 1000 / 29.5 = 0.319 M

Question 2

Balanced equation:
HCl + NH3 =====> NH4Cl
Reaction type: synthesis

Moles of HCl reacted = 18.15 x 0.32 / 1000 =  0.005808 Moles

Moles of NH3 present =  0.005808 Moles

Molarity of NH3 =  0.005808 x x1000 / 10 =  0.5808 M

Mass of NH3 =  0.005808 x 17.03 =  0.0989 gm

Mass of the 10 ml solution = 10 ml / 0.99 gm/ml = 10.10 gm

Mass / Mass percentage = 0.0989 x 100 / 10.10 = 0.979 %

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