1. What is a sign for the thermochemical process of melting NaCl?
2. 150 g sample of metal at 80oC added to 150 g of H2O at 20oC. The temperature rises to 23.3oC. what is aa specific heat of metal? Specific heat of water is 4.18 J/g.oC.
3. Calculate the enthalpy change ?Ho for the reaction:
C3H6(g) + 4.5O2(g) ? 3CO2(g) +3H2O(l)
Hof , kj/mol: C3H6(g) =21; CO2(g)= - 394; H2O= - 286
4. A commercial product called "Instant Car Kooler" containes 10 wt.% of Etanol, and 90 wt.% of water. If the interior of your car is overheated, you spray the product inside and the interior is cooled. To drop the air temperature from 55oC to 25oC requires air to give up 3.6 kj. How many grams of the above product must be used to absorb this heat?
The enthalpy of vaporization for ethanol is 850 j/g, and for water it is 2360 j/g.