4. a) The enthalpy change of combustion of hexane was measured using
a calorimeter containing 200 cm3 of water; 0.5g of hexane (C6H14) was burnt.
The temperature of the water increased by 28.50K.
Calculate the enthalpy change of combustion of hexane.
(c = 4.184 kJ kg-1K-2). Give your answer in kJmol-1.
b) Suggest why this experimental value is less than the standard enthalpy
change of combustion of hexane found in a data book.

When will le chatelier's principle come into effect? at the beginning of a reaction, when there are only reactants when a reaction has reached chemical equilibrium when a catalyst is added to a reaction mixture when a reaction is occurring but not yet at equilibrium

Astudent is given a sample of a blue copper sulfate hydrate. he weighs the sample in a dry covered porcelain crucible and got a mass of 23.875 g for the crucible, lid, and sample. the mass of the empty crucible and lid was found earlier to be 22.652 g. he then heats the crucible to expel the water of hydration, keeping the crucible at red heat for 10 minutes with the lid slightly ajar. on colling, he finds the mass of crucible, lid, and contents to be 23.403 g. the sample was changed in the process to very light clue anhydrous cuso4. if there are again 100.0 g of hydrate, how many grams of cuso4 are in it? how many moles of cuso4? (hint: molar mass of cuso4 = 159.6 g / mole. what per cent of the hydrate is cuso4? you may convert the mass of cuso4 to moles.)

What is the molar mass of potassium nitrate, kno3