In which thermochemical equations would the ΔH be considered a heat of solution? 2NaHCO3(s)→Na2CO3 (s) + H2O (g) + CO2 (g), ΔH = –129 kJ C6H6(s)→C6H6(l), ΔH=+9.87 kJ NH4NO3(s)→NH4+(aq)+NO3–(aq), ΔH=+25.7 kJ/mol 2C8H18(l)+25O2(g)→16CO2(g)+18H2O(l) , ΔH =–5,471 kJ/mol

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.