Answer:
0.44g
Explanation:
Given parameters:
Mass of magnesium hydroxide = 0.645g
Solution
The balanced reaction equation is shown below:
Mg(OH)₂ → MgO + H₂O
From the equation above, we see that the number of atoms are conserved.
To find the mass of magnesium oxide produced, we find the number moles of the decomposed magnesium hydroxide first:
Molar mass of Mg(OH)₂ = 24 + 2(16+1) = 58g/mol
Number of moles of Mg(OH)₂ = 
= 
= 0.011mole
Now, from the balanced equaiton, we know that:
1 mole of Mg(OH)₂ produces 1 mole of MgO
Therefore, 0.011mole of Mg(OH)₂ will produce 0.011mole of MgO
so mass of MgO = number of moles of MgO x molar mass of MgO
Molar mass of MgO = 24 + 16 = 40g/mol
mass of MgO = 0.011 x 40 = 0.44g
Constant:
Test tubes
Independent:
<span>volume of gas
Dependent:
</span>
<span>amount of H2O2 </span>
Answer:
0.022 mol O
Explanation:
Mg3(Si2O5)2(OH)2
We can see that 1 mol of this substance has 3 mol of Mg.
Oxygen altogether is 5*2 (from (Si2O5)2) + 2(from(OH)2) = 10 +2 = 12
So, 1 mol of this substance has 12 mol oxygen.
So, 1 mol of this substance contains 3 mol Mg and 12 mol O, or
ratio Mg : O = 3 : 12 = 1 : 4
1 mol Mg ----- 4 mol O
0.055 mol Mg ---x mol O
x = 0.055*4/1 = 0.220 mol O
They are called spectator ions.
Answer:
The enthalpy change for the reaction is ΔH = - 54.3 kJ/mol
Explanation:
The reaction between HCl and NaOH is a neutralization reaction:
Heat released during neutralization = Heat gained by water
i.e. 
where:
m = total mass of solution
ΔT = change in temperature = 22.8 - 21.5 = 1.3 C
c = specific heat = 4.18 J/g C
As per equation (1): qrxn = -434.7 J
The reaction enthalpy ΔH is the heat released per mole of acid (or base)
