Answer : The mass of oxygen formed must be 3.8 grams.
Explanation :
Law of conservation of mass : It states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.
This also means that total mass on the reactant side must be equal to the total mass on the product side.
The balanced chemical reaction will be,
According to the law of conservation of mass,
Total mass of reactant side = Total mass of product side
Total mass of 
= Total mass of 
As we are given :
The mass of 
= 25.3 grams
The mass of 
= 23.4 grams
So,
Therefore, the mass of oxygen formed must be 3.8 grams.
Answer:
35Cl = 75.9 %
37Cl = 24.1 %
Explanation:
Step 1: Data given
The relative atomic mass of Chlorine = 35.45 amu
Mass of the isotopes:
35Cl = 34.96885269 amu
37Cl = 36.96590258 amu
Step 2: Calculate percentage abundance
35.45 = x*34.96885269 + y*36.96590258
x+y = 1 x = 1-y
35.45 = (1-y)*34.96885269 + y*36.96590258
35.45 = 34.96885269 - 34.96885269y +36.96590258y
0.48114731 = 1,99704989y
y = 0.241 = 24.1 %
35Cl = 34.96885269 amu = 75.9 %
37Cl = 36.96590258 amu = 24.1 %
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)
