Calorimetry can be a confusing topic. Avoid common errors by following these essential tips:

**Always label the units of E (kJ or J) above the E.**This is the most common source of error in calorimetry calculations. Try this quick way to remember the required units of E:*If there’s ΔH in the equation, the units are kJ; otherwise, the units are J.***In E=mcΔT, all the variables refer to the mass of water being heated.**A common error among students is to use the mass of limiting reactant instead of the mass of water. Generally, m in this equation is 100 g or a similar round number.**Never convert ΔT to kelvin.**Temperature changes are the same in kelvin and celcius… never add 273 when finding ΔT.**No calibration step? Use m×c instead.**Because E=mcΔT and E=*Cf*ΔT, it therefore follows that*Cf ≡*m×c. For example, if we’re heating a 100.0 g of water without a*Cf*, we should use*Cf*= 100×4.18 = 418 J K^{-1}instead.**In ΔH = E/n, n denotes the number of moles of limiting reactant.**Never add up the number of moles of reactants: use the number of moles of limiting reagent only.**Calculate twice.**Students most often make mistakes when converting hours or days into seconds. Many answers are therefore wrong by a factor of 60. Do your calculations twice: once while doing the question and again when you check over your answers at the end of the SAC or examination.**Know a ballpark figure.**Neutralisation and solubility reactions tend to have 2-digit ΔH values; combustion reactions tend to have a 3-digit ΔH and explosive reactions tend to have a 4-digit ΔH. If you get a 5-digit ΔH value, you’ve probably forgotten to convert your answer into kilojoules!**Remember the ‘+’ or ‘-‘ sign!**The calculator doesn’t know whether the answer should be positive or negative. Think about it yourself instead: endothermic reactions need a ‘+’ sign and exothermic need a ‘-‘ sign. VCAA awards a whole mark for getting the ‘+’ or ‘-‘ sign correct! It’s possibly the easiest mark in the whole paper.

**Consider getting a home tutor who can answer your questions and explain difficult concepts to you. Students learn much faster with a tutor than on their own.**

Sir, Please explain E = M C Delat T formula ?…in the way how original it was formulated..

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