Mass is a basic property of matter and is made of atoms. Atoms are made of electrons, protons, and neutrons. Protons and neutrons make up the majority of the mass in an atom. Atoms may vary in the number of neutrons they have (called isotopes), and therefore the exact atomic mass may vary from atom to atom
We need to first come up with a balanced equation:
→ 
We know that the molar ratio of hydrogen to oxygen to water now is 4:1:2.
Converting the amount of grams given to moles is as follows:
Hydrogen: 
Oxygen: 
We know now that the limiting reactant is oxygen. We can then know that the number of moles of water are produced are double the number of moles of oxygen used due to the ratio that we established at the beginning - 4:1:2.
So we now can use 6.25 moles of water as the amount produced.
Then we convert moles of water to grams:
Now we know that there are 112.59g of water produced when we start with 50g of hydrogen and 50g of water.
1. Salt is KNO₃<span>
<span>This is a </span>strong acid - strong base<span> <span>reaction. </span></span>HNO</span>₃ is the strong acid<span> <span>and </span></span>KOH is the strong
base<span>. </span><span>
H</span>⁺<span> in the HNO₃<span>
and </span></span>OH⁻<span> <span>of the KOH pair up and make </span></span>H₂O(l)<span>. </span><span>
NO</span>₃⁻<span> <span>and </span></span>K⁺<span> <span>pair up to make </span></span>KNO₃ salt<span>. </span><span>
<span>When writing chemical formulas </span>positive ion comes first<span> <span>and second
is negative ion. The charges should be switched. Since </span></span>positive ion has +1 and negative
ion has -1<span> <span>after
the switching off charges </span>the </span>product should be KNO</span>₃.<span>
Balance
equation is </span><span>
HNO</span>₃<span>(aq) + KOH(aq) → H</span>₂O(l) + KNO<span>₃(aq)</span><span>
<span>
2. Salt is Ca(NO</span></span>₃)₂<span>
</span>This is a strong acid - strong
base<span> reaction. </span>HNO₃ is the strong acid<span> and </span>Ca(OH)₂ is the strong base<span>. </span><span>
<span>
H</span></span>⁺<span> in the HNO₃ and </span>OH⁻<span> of the Ca(OH)₂
pair up and make </span>H₂O(l)<span>. </span><span>
Ca²⁺
and </span>NO₃⁻<span> pair up to make </span>Ca(NO₃)₂ salt<span>. </span><span>
<span>
</span><span>Positive ion is </span>Ca²⁺<span>
which has </span></span>+2 charge<span> and negative ion is</span> NO₃⁻<span> <span>which has </span></span>-1 charge<span>. From switching the charges </span>Ca²⁺ gets 1<span> <span>while </span></span>NO₃⁻ gets 2.<span> Hence, the salt should be </span>Ca(NO₃)₂.<span>
Balanced equation
is
</span>2HNO₃<span>(aq) + Ca(OH)</span>₂<span>(aq) → 2H</span>₂O(l) + Ca(NO<span>₃)₂(aq)</span><span>
<span>
3. Salt is CaCl</span></span>₂<span>
This is a strong acid - strong base<span> reaction. </span>HCl is the
strong acid<span> and </span>Ca(OH)</span>₂ is the strong base<span>. </span><span>
<span>
H</span></span>⁺<span> in the HCl and </span>OH⁻<span> of the Ca(OH)₂
pair up and make </span>H₂O(l)<span>. </span><span>
Ca²⁺
and </span>Cl⁻<span> pair up to make </span>CaCl₂ salt<span>. </span><span>
<span>
</span><span>Positive ion is </span>Ca²⁺
which has </span>+2
charge<span> and negative ion is</span> Cl⁻<span> which has </span>-1
charge<span>. By switching the charges </span>Ca²⁺ gets 1<span> while </span>NO₃⁻ gets 2.<span> Hence, the salt should be </span>CaCl₂.<span>
Balance
equation is
</span><span>2HCl(aq) + Ca(OH)</span>₂<span>(aq) → 2H</span>₂O(l) + CaCl₂<span>(aq)
4. Salt is KCl<span>
</span>This is a strong acid - strong base<span> reaction. </span>HCl is the
strong acid<span> and </span>KOH is
the strong base<span>. </span>
<span>
H</span></span>⁺<span> in the HCl and </span>OH⁻<span> of the KOH pair up and make </span>H₂O(l)<span>. </span><span>
K</span><span>⁺ and </span>Cl⁻<span> pair up to make </span>KCl salt<span>. </span><span>
<span>
</span><span>Positive ion is K</span></span><span>⁺ which has </span>+1
charge<span> and negative ion is</span> Cl⁻<span> which has </span>-1
charge<span>. By switching the charges </span>K⁺ gets 1<span> and </span>Cl⁻ also gets 1.<span> Hence, the salt should be </span>KCl.<span>
Balance
equation is
</span><span>HCl(aq) + KOH(aq) → H</span>₂<span>O(l) + KCl(aq)</span>
