Science Single Award - 4SS0 PearsonEdexcel

Energetics

Gbogbo ọrọ náà

Some reactions release heat and warm their surroundings; others absorb heat and feel cold to the touch. Understanding the energy changes in chemical reactions is essential for everything from choosing fuels to designing hand warmers.

In this lesson you will learn the difference between exothermic and endothermic reactions, how to measure energy changes using simple calorimetry, and how to calculate heat energy using Q = mc delta T.

Ebumnobi

Know that chemical reactions in which heat energy is given out are described as exothermic, and those in which heat energy is taken in are described as endothermic
Describe simple calorimetry experiments for reactions such as combustion, displacement, dissolving and neutralisation
Calculate the heat energy change from a measured temperature change using the expression Q = mcDeltaT
Investigate temperature changes accompanying salts dissolving in water, neutralisation reactions, displacement reactions and combustion reactions

Akọmọ Ojú-ẹkọ

Every chemical reaction involves a transfer of energy between the reacting substances and their surroundings. Some reactions give out heat energy, warming up the surroundings. Others take in heat energy, cooling the surroundings. The direction of energy transfer is one of the most important properties of any reaction.

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Ayẹwo Ẹkọ

Ekele diri gi maka imecha ihe karịrị na Energetics. Ugbu a na ị na-enyochakwa isi echiche na echiche ndị dị mkpa, ọ bụ oge iji nwalee ihe ị ma. Ngwa a na-enye ụdị ajụjụ ọmụmụ dị iche iche emebere iji kwado nghọta gị wee nyere gị aka ịmata otú ị ghọtara ihe ndị a kụziri.

Ị ga-ahụ ngwakọta nke ụdị ajụjụ dị iche iche, gụnyere ajụjụ chọrọ ịhọrọ otu n’ime ọtụtụ azịza, ajụjụ chọrọ mkpirisi azịza, na ajụjụ ede ede. A na-arụpụta ajụjụ ọ bụla nke ọma iji nwalee akụkụ dị iche iche nke ihe ọmụma gị na nkà nke ịtụgharị uche.

Jiri akụkụ a nke nyocha ka ohere iji kụziere ihe ị matara banyere isiokwu ahụ ma chọpụta ebe ọ bụla ị nwere ike ịchọ ọmụmụ ihe ọzọ. Ekwela ka nsogbu ọ bụla ị na-eche ihu mee ka ị daa mba; kama, lee ha anya dị ka ohere maka ịzụlite onwe gị na imeziwanye.

An exothermic reaction: A) Absorbs heat B) Releases heat C) Has no energy change D) Always involves combustion Answer: B
The specific heat capacity of water is: A) 4.2 J/g/degrees C B) 42 J/g/degrees C C) 0.42 J/g/degrees C D) 420 J/g/degrees C Answer: A
Which of these is an endothermic process? A) Combustion of methane B) Neutralisation C) Thermal decomposition of calcium carbonate D) Rusting of iron Answer: C
In a calorimetry experiment, the temperature of 100 g of water rises by 10 degrees C. The energy transferred is: A) 420 J B) 1000 J C) 4200 J D) 42000 J Answer: C
A cold pack works because the reaction inside is: A) Exothermic B) Endothermic C) Neutral D) Reversible Answer: B