2.25 I believe
Hope this helped!
STSN
Answer:
The process where substance react with oxygen is called combustion.
Explanation:
When substance react with oxygen combustion is occur. The substance which burned is called fuel and in this process large amount of heat is released to the surrounding. It is exothermic process.
For example:
4Li + O₂ → 2Li₂O
2Mg + O₂ → 2MgO
S + O₂ → SO₂
The product which is formed as a result of combustion reaction are called oxides.
In given examples we can see that lithium, magnesium and sulfur react with oxygen and product formed is oxides of respective elements such as lithium oxide ( Li₂O), magnesium oxide (MgO) and sulfur oxide ( SO₂ ).
: If you mean table salt i.e. sodium chloride. It is held together by ionic bonds between sodium (Na+) and chloride (Cl-) ions. The sodium ions have a positive charge and the chlorine ions have a negative charge. Since opposite charges attract, they form ionic bonds. Ionic bonds are nothing more than the attraction between positive and negative ions.
Answer:
b) 2.0 mol
Explanation:
Given data:
Number of moles of Ca needed = ?
Number of moles of water present = 4.0 mol
Solution:
Chemical equation:
Ca + 2H₂O → Ca(OH)₂ + H₂
now we will compare the moles of Ca and H₂O .
H₂O : Ca
2 : 1
4.0 : 1/2×4.0 = 2.0 mol
Thus, 2 moles of Ca are needed.
Percent strength (% w/w) of a solution is defined as the amount of solute present in 100 g of the solution.
Given data:
Mass of the solute, potassium chloride = 62.5 g
Volume of water (solution) = 187.5 ml
We know that the density of water = 1 g/ml
Therefore, the mass corresponding to the given volume of water
= 187.5 ml * 1 g/1 ml = 187.5 g
We have a solution of 62.5 g of potassium chloride in 187.5 g water
Therefore, amount of solute in 100 g of water= 62.5 * 100/187.5 = 33.33
The percentage strength = 33.33 %
