Answer:
#1 You get valid data for one.
#2 Not measuring accurately can have some bad consequences.
#3 If you mix the wrong amount of chemicals you can end up getting yourself or worse other people hurt.
#4 When making food you need to measure the amount of sugar or salt you put into the dish or else your face will be this
Firstly, the chemical equation between the calcium metal and water will be:
Ca(s) + 2 H₂O(l) → Ca(OH)₂(aq) + H₂(g)
We can see from the equation the bubbles of hydrogen gas which are formed during the reaction stick to the surface of the metal and hence calcium floats on water.
The other metal that will float on the water during the reaction is magnesium which have the same chemical behavior like calcium, we can illustrate that by the chemical equation:
Mg(s) + 2 H₂O(l) → Mg(OH)₂(aq) + H₂(g)
What chemistry question....?
If it's an endothermic reaction, then that means heat is being added to the system therefore H>0. Entropy is disorder, and since there are more moles on the products side, entropy is increasing therefore S>0 as well.