Acids, Bases and Rates of Reaction Flashcards
Chemical Changes & Structures
What is the rate of a reaction?
The rate of a reaction is how fast the reaction takes place.
What is a chemical reaction?
A chemical reaction is a change in which a new substance is formed.
How can you tell that a reaction is taking place?
- Effervescence
- Colour change
- Temperature change
- Precipitation
The rate of a reaction can be increased by…
- Increasing the temperature.
- Increasing the concentration of the reactant.
- Decreasing the particle size of the reactant.
- Adding a catalyst
What happens during a reaction?
During a reaction, particles collide to combine and produce new products.
What is surface area in a reaction?
In a reaction, surface area refers to how spread out the particles are (eg. a powder has high surface area, whereas a stone has low surface area).
What is a catalyst?
A catalyst is a substance that is used to speed up [or slow down] the rate of a reaction without affecting the end result or getting affected itself.
What is the formula to calculate the rate of a reaction?
Rate = Change in Quantity/Change in Time R = ΔQ/ΔT
What is an exothermic reaction?
An exothermic reaction is one in which heat is given out. Eg. Burning anything.
What is an endothermic reaction?
An endothermic reaction is one in which heat is absorbed.
Eg. Making ammonia fertilizers.
How many hexillions are in 1 mole?
1 mole = 602 hexillions
What is the Gram Formula Mass?
The GFM is the weight of 1 mole of that substance.
What is the moles, mass and GFM formula?
n = m/GFM where n is the number of moles and m is the mass of the substance.
What is concentration?
The number of particles in a set volume.
What is the moles, concentration and volume formula?
n = CV where n is the number of moles, C is the concentration and V is the volume.
What is the pH scale?
A number scale used to measure whether the solution of a substance dissolved in water is:
- acidic
- alkaline
- or neutral.
It also tells us how acidic or alkaline a solution is.
How can the pH level be measured?
pH paper, universal indicator, pH meter - electronic device.
What are the effects of diluting:
a) an acid?
b) an alkali? [with water]
a) pH increases to 7
b) pH decreases to 7.
What are bases?
Bases are substances that release hydroxide ions in an aqueous solution. They neutralize acidic solutions.
What is an alkali?
A base that is soluble in water.
What are acids?
Acids are substances which release hydrogen ions in an aqueous solution. They neutralize basic/alkaline solutions.
Where does acid rain come from?
- Carbon dioxide.
- Nitrogen dioxide [emissions from car exhausts].
- Sulphur dioxide [emissions from burning coal].
Acid rain can occur naturally but can also come from burning fossil fuels.
What are the damages of acid rain?
- Attacks limestone buildings.
- Destroys trees or plants.
- Makes soil acidic.
- Contaminates lakes and rivers, killing aquatic life.
What is are indicators?
Substances that show the pH of a solution.
What are the different colour changes for indicators with respect to acids and bases?
Litmus: Acid - Red, Base - Blue.
Phenolphthalein: Acid - Colourless, Base - Pink.
Methyl Orange: Acid - Pink, Base - Orange.
Thymol Blue: Acid - Yellow, Base - Blue.
What are spectator ions?
Ions which are present during a reaction but do not take part in the reaction.
What is a neutralisation reaction?
A reaction in which an acid and an alkali cancel each other out and react to give a salt and water as products.
What is titration?
A practical method used to work out the unknown concentration of an acid or alkali by neutralising it with an acid or alkali of a known concentration.
What is a strong acid/alkali?
One that dissociates completely into ions in a solution.
What is a weak acid or alkali?
One that dissociates only partially into ions in a solution.
How is the pH of a salt solution determined?
By the strength of the parent acid and base.
What is the concentration-pH formula?
If the concentration of H+ ions is expressed in the form of 10^a, then pH = -1*a
