Chemistry Questions that need answers Please?

22. The heat of combustion of methane, CH4, is -890 kJ/mol. What mass of methane must be burned to produce 250 kJ of heat?


a)0.223 g


b)3.56 g


c)4.49 g


d)57.0 g





24. Why does the rate f a reaction increase when temperature increases?


a) The voume increases.


b) The kinetic energy of the products increases


c) The number of effective collisions increases.


d) The potential energy of the reactants increases.





25. How does the addition of a catalyst affect the change in enthalpy of a reaction?


a) no effect


b) increases


c) decreases


d)decreases only if the reaction is endothermic





26. which describes the bonding found in sodium hydrogen carbonate, NaHCO3?


a)only ionic


b) onlky covalent


c) both ionic and covalent


d) both ionic and metallic





27. What change in the oxidation number of chlorine occurs when KClO3 is decomposed?


2KClO3 %26gt; 2KCl + 3O2


a) + 5 to -1


b) +1 to -1


c)-2 to -1


d) +2 to -1

Chemistry Questions that need answers Please?
22)C


24)C


25)A


26)A


27)A
Reply:22. 250/890 * 16g/mol = 4.49g


24. C (More active molecules)


25. A (It only lowers activation energy)


26. A


27. A (-2*3+1 = -5) to (-1)