Controlling reactions

Chemistry (Combined Science) · GCSE · OCR · OCR GCSE Combined Science A (Gateway Science) — Chemistry — Foundation (J250) · Specification point · C5.1 · Monitoring and controlling chemical reactions

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Learning Objectives

C5.1 Controlling reactions

Summary The rate and yield of a chemical reaction can be altered by changing the physical conditions. Underlying knowledge and understanding Learners should be familiar with the action of catalysts in terms of rate of reaction. They should know the term surface area and what it means. Common misconceptions Learners often misinterpret rate graphs and think that catalysts take part in reactions and run out/get used up.

Reference	Mathematical learning outcomes	Maths skills
$CM5.1i$	$arithmetic computation, ratio when measuring rates of reaction$	$M1a, M1c$
$CM5.1ii$	$drawing and interpreting appropriate graphs from data to determine rate of reaction$

Learning outcomes	To include	Maths	Working scientifically	Practical suggestions
$C5.1a suggest practical methods for determining the rate of a given reaction$		$M1a, M1c$	$WS1.2b, WS1.2c, WS1.2d, WS2a, WS2b$	$Rate of reaction experiments. (PAG C5) Disappearing cross experiment. (PAG C5) Magnesium and acid, marble chips and acid. (PAG C5)$
$C5.1b interpret rate of reaction graphs$	$1/t is proportional to rate and gradients of graphs (not order of reaction)$	$M4b, M4c$	$WS1.3a, WS1.3b, WS1.3c, WS1.3d, WS1.3e, WS1.3f, WS1.3g, WS1.3h, WS1.3i, WS2b$	$Marble chips and acid or magnesium and acid experiments either measuring reaction time or the volume of gas over time. (PAG C4, PAG C5)$
$C5.1c describe the effect of changes in temperature, concentration, pressure, and surface area on rate of reaction$		$M4d, M4e$	$WS1.4c$	$Varying surface area with marble chips and hydrochloric acid. (PAG C5)$
$C5.1d explain the effects on rates of reaction of changes in temperature, concentration and pressure in terms of frequency and energy of collision between particles$			$WS1.4c$	$Reaction of magnesium and acid with different temperatures of acid - measure reaction times. (PAG C5)$
$C5.1e explain the effects on rates of reaction of changes in the size of the pieces of a reacting solid in terms of surface area to volume ratio$		$M1c$
$C5.1f describe the characteristics of catalysts and their effect on rates of reaction$
$C5.1g identify catalysts in reactions$			$WS1.4a$	$Catalysis of hydrogen peroxide with various black powders including MnO₂. (PAG C5) Catalysis of reaction of zinc with sulfuric acid using copper powder. (PAG C5).$
$C5.1h explain catalytic action in terms of activation energy$	$reaction profiles$
$C5.1i recall that enzymes act as catalysts in biological systems$

Controlling reactions (C5.1) | OCR GCSE Combined Science A (Gateway Science) — Chemistry — Foundation (J250) | KnowledgeSet