C3.3 - Types Of Chemical Reactions Flashcards
What is a redox reaction?
A redox reaction is a reaction in which reduction and oxidation happen at the same time
What is reduction and oxidation?
- Reduction is the loss of oxygen from a substance.
- Oxidation is the gain of oxygen by a substance.
- Reduction is the gain of electrons from a
substance. - Oxidation is the loss of electrons from a substance.
What is an oxidising agent?
A substance that oxidises another substance by donating oxygen or by accepting electrons.
What is a reducing agent?
A substance that reduces another substances by accepting oxygen or by donating electrons.
What do half equations show?
A half equation shows the change that happens to one reactant in a reaction.
What is an acid?
An acid is a substance that releases H+(aq), hydrogen ions, when it is dissolves in water to make an aqueous solution.
What is a base?
A substance that can neutralise acids.
What is an alkali?
- An alkali is a base that can dissolve in water.
- Releases hydroxide ions, OH- (aq), when it
dissolves in water.
What does the pH of a solution show?
- The pH of a solution describes its relative acidity or alkalinity. - pH < 7 means acidic. - pH = 7 means neutral. - pH > 7 means alkaline.
How do you measure pH with a pH meter?
- First need to calibrate the pH meter to get
accurate measurements. - Wash the pH probe with water, then put it into a
calibration buffer. - Adjust the reading to match the pH of the buffer
solution. - Wash the probe with water then put it into the
solution and record the reading on the metal. - Make sure to wash the probe between each
measurement to make sure that the probe is not
contaminated with the previous sample as this
would affect the reading.
What is a neutralisation reaction?
Neutralisation is the reaction between an acid and a base to form a salt and water.
How do you predict the salt produced in a neutralisation reaction?
- The first part comes from the metal in the base
or alkali. - The second part of the name comes from the
acid used.
What ionic equation models neutralisation in solution?
H+(aq) + OH-(aq) -> H2O(l)
Give the formula when acids react with carbonates.
acid + metal carbonate -> Salt + Water + Carbon dioxide (gas - released as bubbles in the reaction)
Why does a lump of calcium carbonate appear to dissolve in water even though its insoluble in water?
The salt formed is aqueous and the carbon dioxide is released as bubbles which is why a lump of insoluble calcium carbonate appears to dissolve if you add acid to it.
What is the term that chemists use to describe bubbling or fizzing?
Effervescence
Give the word equation when an acids reacts with a metal?
Acid + Metal -> Salt + Hydrogen (gas - released as bubbles)
If magnesium is insoluble why does a piece of magnesium ribbon appear to dissolve if you put it into acid?
Soluble magnesium salt is formed and the hydrogen gas is released as bubbles which makes the magnesium appear to dissolve.
What is the difference between a dilute acid and concentrated acid?
A dilute acid contains a low ratio of acid to volume of solution whereas a concentrated acid contains a high ratio of acid to volume of solution.
What is the difference between weak and strong acids?
- Weak acids partially ionise which means only a
small fraction of their molecules release H+ ions
when dissolved in water. - Strong acids fully ionise which means all their
molecules H+ ions when dissolved in water. - Weak acids use that double arrow symbol to
show the hydrogen ion and negatively charged
ion reaction not going fully to completion.
What happen as the concentration H+ ions increases by a factor in 10 in an aqueous solution?
The pH of the solution decreases by 1.
What does a pH titration curve show?
A pH titration curve shows the effect on pH of changing the hydrogen ion concentration during a neutralisation reaction.
