balancing equations?

Question

im having trouble doing my chem lab. writing balencing equations using s,l,g,aq can someone help me?

1. light the bunsen burner. ignite a 1cm piece of magnesium ribbon and place it in the evarpotaing dish

2. take a small 50 mL beaker and fill it with 20 mL of water. put 2 drops of phenolphthalein into the water. add the white powder from step 1 to the beaker.

3. place a small amount of the calcuim carbonate into the test tube.ignite a wood splint. removie the test tube from the flame and put the wood splint into the mouth of the test tube

4. put 10 mL of HCL into a new test tube. drop .5cm pice of magnesium ribbon into the test tube. insert a burning splint into the mouth of the tube.

thank you !!!

Answer 1

1. 2Mg (s) + O2 (g) ---> 2MgO (s)

2. MgO (s) + H2O (l) -----> Mg(OH)2 (aq) H+ (aq)

3. CaCO3 (s) + 2H+ (aq) ---> H2O (l) + CO2 (g) + Ca2+ (aq)

4. Mg (s) + 2H+ (aq) --> Mg2+ (aq) + H2 (g)

Answer 2

When you have a solid, you use (s) to show that
When you have a liquid, you use (l) to show that
When you have a gas, you use (g) to show that
When you have a substance that dissolves in water you use (aq) to show that. The "aq" stands for "aqueous" and means you used water as a solvent.

1. The Mg (which is a solid) reacted with oxygen in the air (which is a gas) and produced magnesiuim oxide (which is a white solid).
[this is a synthesis reaction)

2Mg(s) + O2 (g) = 2MgO(s)

2. The magnesium oxide (which is a solid) combined with the water (which is a liquid) to form a new compound, magnesium hydroxide which does NOT dissolve in water, so it is a solid.
[this is also a synthesis reaction]

MgO(s) + H2O(l) = Mg(OH)2 (s)
(you don't use "aq" here because the MgO is not dissolving in the water; it is actually reacting with it).

3. Calcium carbonate is a solid that decomposes when heated into calcium oxide (a solid) and carbon dioxide (a gas).
[so this is a decompostion reaction]

CaCO3(s) = CaO(s) + CO2(g)

4. The magnesium, (which is a solid), reacts with a water solution of HCl (aqueous) and forms magnesium chloride which is soluble in the water (so it is aqueous) and hydrogen which is a gas.
[this is a single replacement reaction]

Mg(s) + 2HCl(aq) = MgCl2(aq) + H2(g)

If you've learned about ionic equations you would split the HCl into its two ions because it does that in water; you would also split the MgCl2 into its two ions because it does that in water. You would then have:

Mg(s) + 2H+(aq) + 2Cl-(aq) = Mg2+(aq) + 2Cl-(aq) + H2(g)

And THEN, if you've learned about NET ionic equations you should recognize that the Cl- hasn't changed in the reaction (its called a "spectator ion") and so it is usually eliminated and the FINAL equation becomes:

Mg(s) + 2H+ = Mg2+(aq) + H2(g)