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what are the answers to these stoichiometry equations?1) How many atoms of chlorine are...

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kasane | Student, College Freshman

Posted August 7, 2012 at 5:34 AM via web

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what are the answers to these stoichiometry equations?

1) How many atoms of chlorine are in 19.0 grams of MgCl2?

2) What is the volume of 2.60 moles of CO2(g) at STP?

3) What is the mass of 20.00 liters of N2(g) if the temperature is     0 degrees Celsius and the pressure is 101.3 kPa?

4) How many grams of NaOH(s) would you need to prepare 500. mL of 0.160M NaOH(aq)

5) WHat volume of 12M HCl(aq) solution(concentrated hydrochloric acid) is needed to prepare 250. mL of 0.100M solution?

6) What is the resulting concentration of KCl when 100. mL of 0.250M KCl(aq) are added to 400. mL of water?

7) What volume of 0.360 M Mg(NO3)3(aq) contains 0.120 moles of NO3^-1 ions?

1 Answer | Add Yours

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llltkl | College Teacher

Posted August 19, 2012 at 6:52 AM (Answer #1)

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1. 95 gms contain 2N atoms of chlorine 

so 19 gm contains 1/5 x 2 N (where N = 6.023 x 10EXP23) atoms of chlorine.

2. 2.60 x 22.4 litres.

3. standard pressure is 101.3 KPa and standard temperature 0 degree Celcius, hence the stated conditions are STP,

so at STP 22.4 lit N2 has a mass of 28 gms

hence 20.0 lit should have a mass of 20x28/22.4 gms = 25 gms.

4. 40 x 0.16 x 500/1000 = 3.2 gms

5. 250 x 0.1/12 = 2.083 ml

6. 100 x 0.25/500 = 0.05 M

7. 0.36 x 3 moles of NO3-1 present in 1000 ml soln

so 0.12 mole should be present in 1000 x 0.12/(0.36x3) = 111.11 ml soln.

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