Rates Of Reactions + Percentage Yield Flashcards
(14 cards)
What is the equation for rate of reactions?
Rate of reaction = mass of reactants / time
What is the gradient of a mass x time graph equal to? And how would you find the rate of reaction at a specific point on the graph?
-The rate of the reaction
- find the gradient of a tangent at the point
What is percentage yield?
How much product is produced as a proportion to the maximum of how much could have been made
What is the equation for percentage yield?
(Real yield / theoretical yield ) x100
What factors mean percentage yield is never 100%?
- incomplete reactions (some reactions too slow)
- waste (e.g. material stuck to apparatus)
- side reactions (unexpected additional reactions)
- extraction (is difficult to separate product from reactants)
What is real yield?
Mass of product generated from a reaction
What is theoretical yield?
Maximum mass of product that could possibly be created from a reaction
What is le chatelier’s principle?
If any conditions in a reversible reaction at equilibrium change, the closed system will adapt to counteract the change by moving the position of equilibrium
What three things can change the position of equilibrium?
- temperature
- pressure (gas only)
- concentration
What will occur to the position of equilibrium if there is a decrease in pressure?
Position of equilibrium will move towards side that produces more gas molecules
If you increase the concentration of products, which direction will the equilibrium position move to?
Shift equilibrium position towards products
What is the rate of reaction?
How fast reactants are turned into products / how fast the reaction occurs
Why is a fast rate of reaction in industry bad?
- expensive to generate conditions for fast reactions
- safety concerns over fast reactions
If the temperature of a reaction decreases, will the equilibrium position move towards the endothermic, or exothermic side?
Exothermic
