In: Chemistry
1. Calculate the enthalpy change, ΔH, for the formation of 1 mole of strontium carbonate (the material
that gives the red color in fireworks) from its elements.
Sr(s) + C(s) + 1.5 O2(g) → SrCO3(s)
Use the following information:
2 Sr(s) + O2(g) → 2 SrO(s) ΔH = -1184 kJ
SrO(s) + CO2(g) → SrCO3(s) ΔH = -234 kJ
C(s) + O2(g) → CO2(g) ΔH = -394 kJ
2. Write chemical reactions that describe the formation of the following compounds:
a. Silver sulfate
b. Ammonium bromide
c. Tin (IV) phosphate
2 Sr(s) + O2(g) → 2 SrO(s) ΔH = -1184 kJ -----------------> 1
SrO(s) + CO2(g) → SrCO3(s) ΔH = -234 kJ ---------------->2
C(s) + O2(g) → CO2(g) ΔH = -394 kJ -------------------->3
equation 1 divide with 2
Sr(s) + 1/2O2(g) → SrO(s) ΔH = -592 kJ ------------> 4
addition with equation 4 and 3
Sr(s) + 1/2O2(g) → SrO(s) ΔH = -592 kJ
C(s) + O2(g) → CO2(g) ΔH = -394 kJ
--------------------------------------------------------------
Sr(s) + C(s) +3/2O2(g) ---------. SrO(s) + CO2(g) ΔH = -986Kj addition
SrO(s) + CO2(g) → SrCO3(s) ΔH = -234 kJ
--------------------------------------------------------------------------------------
Sr(s) + C(s) + 3/2O2(g) --------------> SrCO3(s) ΔH = -1220Kj
Sr(s) + C(s) + 1.5O2(g) --------------> SrCO3(s) ΔH = -1220Kj
2.
a. Silver sulfate
2Ag(s) + S(s) + 2O2(g) -----------------> Ag2So4(s)
b. Ammonium bromide
1/2N2(g) +2H2(g) + 1/2Br2(l) ---------------> NH4Br(s)
c. Tin (IV) phosphate
3Ti(s) + P4(s) + 8O2(g)------------------> Ti3(PO4)4(s)