...Chemical Reactions Flashcards
What happens when sodium and chlorine react with one another?
When a sodium atom and a chlorine atom react with one another, an ionic bond is formed with sodium (2, 8, 1) losing its outer shell electron to chlorine (2, 8, 7), completing the outer shell of the chlorine atom.
The resultant substance is sodium chloride.
Sodium + chlorine -> sodium chloride
The balanced chemical equation is as follows:
2Na(s) + Cl2(g) -> 2NaCl(s)
Two hydrogen molecules (two pairs of atoms) meet one oxygen molecule (pair of two atoms) in a gaseous state. What does this produce? Give the word and chemical equations..
This produces liquid water as a product.
4 hydrogen (g) + 2 oxygen (g) -> 2 water (l)
2H2 (g) + O2 (g) -> 2H2O (l)
What happens when magnesium and oxygen react with one another?
Magnesium (2, 8, 2) loses two electrons to oxygen (2, 6), completing both outer shells in an ionic bond.
Magnesium oxide (MgO) is formed.
The balances chemical equation is as follows:
2Mg(s) + O2(g) -> 2MgO(s)
How is calcium chloride formed?
A Ca atom (2, 8, 8, 2) loses its two outer electrons to two Cl atoms (2, 6, 7)
A stable ionic bond is formed and the resultant substance is calcium chloride.
The balances chemical equation is as follows:
Ca(s) + Cl2(g) -> CaCl2(s)
What happens when the alkali metals react with water? Give the standard word equation for the reaction.
They all react with water to produce a metal hydroxide and hydrogen.
The metal hydroxide is an alkaline hydroxide, hence the name “alkali” metals.
Metal + cold water -> metal hydroxide + hydrogen
What happens when sodium reacts with water?
2Na(s) + 2H2O(l) -> 2NaOH(aq) + H2(g)
Sodium + water -> sodium hydroxide + hydrogen
- the sodium floats as it is less dense than water
- it melts because it’s melting point is low and a lot of heat is produced by the reaction
- because the hydrogen is not given off symmetrically, the ball of sodium is pushed around the surface of the water
- a white trail is formed in the water, which is the sodium hydroxide, and this dissolves to make a strongly alkaline solution
What are the chemical equations for lithium reacting with water?
2Li(s) + 2H2O(l) -> 2LiOH(aq) + H2(g)
Lithium + water -> lithium hydroxide + hydrogen
What happens when potassium reacts with water and what are the chemical equations?
2K(s) + 2H2O(l) -> 2KOH(aq) + H2(g)
Potassium + water -> potassium hydroxide + hydrogen
- a faster reaction that sodium, the potassium floats to the surface due to a lower density than water and is pushed violently around the surface by the hydrogen that is being emitted
- enough heat is produced to ignite the hydrogen, which burns with a lilac flame
- the reaction often ends with the potassium spitting around
What happens when magnesium reacts with hydrochloric acid?
- liquid will effervesce
- hydrogen gas will be given off
- reaction will be exothermic
Mg(s) + 2H+(aq) + 2Cl-(aq) -> Mg2+(aq) + 2Cl-(aq) + H2(g)
- HCl splits up in water which is why they are down as separate ions
- the electrons are taken from the magnesium by the hydrogen ions while the chlorine ions remain unchanged
What happens when magnesium reacts with sulphuric acid?
- liquid will effervesce
- hydrogen gas will be given off
- reaction will be exothermic
Mg(s) + 2H+(aq) + SO4 2-(aq) -> Mg2+(aq) + SO4 2-(aq) + H2(g)
- the electrons are taken from the magnesium by the hydrogen ions while the sulphate ions remain unchanged
Describe how ammonium chloride can be used in a “reversible” reaction…
ammonium chloride (»arrow symbol«) Ammonia + hydrogen chloride
Ammonium chloride (a white solid) can break down to form ammonia and hydrogen chloride.
Ammonia and hydrogen chloride (colourless gases) can react to form ammonium chloride again.
Describe a reversible reaction that is often used to test for water..
Anhydrous copper (II) sulphate + water (»«) blue hydrated copper (II) sulphate
This reaction is used to test for water as the white solid turns blue in the presence of water
What happens when chlorine is added to sodium bromide solution?
When chlorine is added to sodium bromide solution, the bromine is DISPLACED by the chlorine.
The solution turns brown, and the brown colour is the displaced bromine.
The chlorine has gone to form sodium chloride.
The Cl and Br have swapped places.
Chlorine + sodium bromide -> sodium chloride + bromine
Cl2(aq) + 2NaBr(aq) -> 2NaCl(aq) + Br2(aq)
Give the chemical and word equations for iron reacting with sulphuric acid…
Iron + sulphuric acid -> iron sulphate + hydrogen
Fe(s) + H2SO4(aq) -> FeSO4(aq) + H2(g)
