Which property can be altered by a physical change? A. composition
B. melting point
C. appearance
D. density

What mass of natural gas (ch4) must you burn to emit 276 kj of heat?

)benzene and toluene form nearly ideal solutions. consider an equimolar solution of benzene and toluene. at 20 °c the vapour pressures of pure benzene and toluene are 9.9 kpa and 2.9 kpa, respectively. the solution is boiled by reducing the external pressure below the vapour pressure. calculate (i) the pressure when boiling begins, (ii) the composition of each component in the vapour, and (iii) the vapour pressure when only a few drops of liquid remain. assume that the rate of vaporization is low enough for the temperature to remain constant at 20 °c.

If you used the method of initial rates to obtain the order for no2, predict what reaction rates you would measure in the beginning of the reaction for initial concentrations of 0.200 m, 0.100 m, & 0.050 m no2.