energy cannot be created or destroyed, only changed from one form to another
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During chemical reactions heat is...
... given out to the surroundings or taken in from the surroundings
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What happens during an exothermic reactions?
heat is given out, the temperature of the surrounding solution rises
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What happens during an endothermic reaction?
heat is take in, the temperature of the surrounding solution falls
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What defines temperature change?
final temp - intial temp
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What is the cpe of the products in an exothermic reaction and endothermic reaction? What is the energy change?
the cpe of the products is less that that of the reactants. energy change is negative. endothermic is vice versa
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What is the unit for energy chagne?
kJ/mol
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How do you define energy change?
final energy - intial energy
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What is concentration?
the amount of a solute chemical (grams or moles) in a given volume of solution (cubic decimetre)
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What is the formula for concentration?
conc. (mol/dm3 or M) = no. of moles/ volume (dm3)
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How do you define temperature change?
final temp -initial temp
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What is the temperature change in exothermic and endothermic reactions?
temp. - up for exo, temp. down - endo
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How do you calculate energy change?
E=mas of water * specific heat capacity * corrected temperature change, convert the energy into kilojoules and calculate what one mole is. insert sign for enod or exo
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What is the density and specific heat capacity of water?
1g/cubic cm and 4.2J/g/C
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Describe fuels
substances that give out heat when they burn (combustion is exothermic)
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