1. Write the balanced chemical equation for the decomposition of aqueous hydroge

Question

1. Write the balanced chemical equation for the decomposition of aqueous hydrogen peroxide, H2O2.

2. A student performed an experiment in which they collected hydrogen gas from the reaction of magnesium with hydrochloric acid.

The reaciton is: Mg(s) +2HCL(aq)---->H2(g) +MgCl2 (aq).

The data collected is shown: Mass of Mg=0.100g, Volume of HCl=10 ML, Volume of H2 collected =57.5 mL temp of H2=22 degrees celsius, barometric pressure=29.94 inHg.

a) Barometric pressure in atmospheres?

b) water vapor pressure in atmospheres?

c) pressure of the hydrogen in atmospheres?

d) volume of hydrogen in liters?

e) temp in kelvin?

f) moles of hydrogen collected?

g) moles of hydrocholoric acid reacted?

h) molarity of hydrocholric acid?

i) if the bottle claimed that the molarity was 0.510M what is the percent error?

Explanation / Answer

1. The decomposition of is H2O2(aq) -->H2O(aq)+0.5O2

the reaction of magnesium with hydrochloric acid.

The reaciton is: Mg(s) +2HCL(aq)---->H2(g) +MgCl2 (aq).

Mass of Mg=0.100g, Volume of HCl=10 ML, Volume of H2 collected =57.5 mL temp of H2=22 degrees celsius, barometric pressure=29.94 inHg.

a. 29.92 inchesof Hg= 1 atm, 29.94 inches= 29.94/29.92 atm= 1.0 atm

b. From Antoine equation for water, lopSat(mm Hg)= 8.07131-1730.63/(t+233.426), psat = vapor pressure of water at temperature t ( t in deg.c), log Psat (mm Hg)= 8.07131-1730.63/(22+233.426), psat= 19.76 mm Hg

760 mm Hg= 1atm, vapor pressure of water= 19.76/760 atm =0.026 atm

partial presure of hydrogen , P= total pressure- saturation vapor pressure of water 1-0.026 =0.974 atm

Volume of hydrogen , V = 57.5 ml. 1000ml= 1L, Volume of hydrogen= 57.5/1000 L=0.0575L

temperatture is 22 deg.c, temperature in K= temperature in deg.c +273= 22+273= 295K

R= gas constant =0.0821 L.atm/mole.K

moles of hydrogen collected (n) = PV/RT=0.974*0.0575/(0.0821*295)= 0.0023 moles

moles of Mg= mass/atomic weight= 0.1/24=0.0042, thiis is excess reactant ( beause only 0.002 moles of H2 is formed from the reaction

from the reaction Mg+2HCl --------->MgCl2+ H2, 1 moles of Hydrogen requires 1 mole of Mg and 2 moles of HCl.

moles of HCl required 0.0023*2= 0.0046 moles of HCl. volume of HCl given = 10ml, expressing this in liters, volume of HCl =10/1000, molarity of HCl= moles/ volume in Liters =0.0046*1000/10=0.46M

molarity specified = 0.510M

% error = 100*{(0.510-0.460)/0.510}=9.8%

h) molarity of hydrocholric acid?

i) if the bottle claimed that the molarity was 0.510M what is the percent error?

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.