Chemical Reactions Flashcards
What is the difference between a physical change and a chemical change?
A physical change is reversible and doesn’t form a new substance e.g. ice melting (change of state) whereas a chemical change is irreversible and does form a new substance e.g. wood burning
Give 3 signs of a chemical change
Temperature change
Colour change
Bubbling/fizizng
What is the chemical test for hydrogen?
Lit spill - squeaky pop
What is the chemical test for oxygen?
Glowing spill - relights
What is the chemical test for carbon dioxide?
Bubble gas through lime water - turns cloudy
What is the chemical test for water?
Add addhedrons copper sulfate - turns blue
What is the conservation of mass?
The mass of the reactants is equal to the mass of the products in a chemical reaction. (It may not seem like it as gas could escape which would make the mass of the product seem less)
What is the equation for oxidation?
Metal + oxygen -) metal oxide
What is the word and symbol equation for the oxidation of magnesium
Magnesium + oxygen -) magnesium oxide Mg + O2 -) MgO2
Why does mass appear to increase when oxidation of metals takes place?
The mass of oxygen in the air that reacts with the metal isn’t measured at the start but at the end it is bonded to that metal and the mass of the products appears to be higher
What is neutralisation?
When an acid and an alkali react
What is thermal decomposition?
The breakdown of carbonates using heat. If we were to measure the mass during the reaction it would appear to go down as one of the products of the reaction is a gas that is released into the air.
What is the equation for thermal decomposition?
Metal carbonate -) carbon dioxide + metal oxide
What is the word and symbol equation for the thermal decomposition of calcium carbonate?
Calcium carbonate -) carbon dioxide+ calcium oxide CaCO3 -) CO2 + CaO
What are the products of complete combustion?
Carbon dioxide, water
What are the products of incomplete combustion?
Carbon (soot), carbon monoxide (toxic gas)
What is the equation for complete combustion?
Blank + oxygen -) carbon dioxide + water
What is reduction?
A loss of oxygen from a compound
What are the rules for balancing equations?
End up with same number of each atom either side of arrow.
Can’t change small numbers at end.
Only add big numbers in front (multiplies everything by that number)
Balance the following:
H2 +Br2 -) HBr
K + Cl2 -) KCl
C + O2 -) CO
H2 + O2 -) H2O
H2 + Br2 -) HBr
Na + Cl2 -) NaCl
H2 + Br2 -) 2HBr
2K + Cl2 -) 2KCl
2C + O2 -) 2CO
2H2 + O2 -) 2H2O
H2 + Br2 -) 2HBr
2Na + Cl2 -) 2NaCl
What is a precipitation reaction?
Where 2 solutions mix together to form a solid- that solid is insoluble (doesn’t dissolve). We call this a precipitate which looks like a cloudy suspension
What things are soluble- not precipitates (does dissolve)?
All sodium, all potassium, all ammonium, all nitrates
What things are insoluble- precipitates (doesn’t dissolve)?
Most carbonates, most hydroxides, most oxides, most lead compounds, most silver compounds, Barium Sulfate
What is an exothermic reaction?
Where heat is given out to the surroundings, the temp increases
