Answer:
there are 2970000cm in 29.7km
Explanation:
Answer:
The ΔH of the reaction is + 12.45 KJ/mol
Explanation:
Mass of water= 100ml = 100g. (You should always assume 1cm3 of water as 1g)
heat capacity of water = 4.18 Jk-1 Mol-1
Change in temperature = (19.86 - 25.00) = -5.14 K (This is an endothermic reaction because of the fall in temperature)
Molar mass of NaHCO3 = 84 g/mol
Mole of NaHCO3 = 14.5 / 84 = 0.173 mol
Step 1 : Calculate the heat energy (Q) lost by the water.
Q = M x C x ΔT
Q = -100 x 4.18 x (-5.14)
Q = 2148.5 joules
Q = 2.1485 K J
Step 2: Calculating the ΔH of the reaction?
ΔH = Q / number of moles of NaHCO3
ΔH = 2.1485 / 0.173
ΔH = 12.42 KJ/mol
Answer:
1.12 moles of MgCl₂
Explanation:
Given parameters:
Mass of Mg(OH)₂ = 65g
Unknown:
Number of moles of MgCl₂ = ?
Solution:
To solve this problem, obtain a balanced reaction equation first;
Mg(OH)₂ + 2HCl → MgCl₂ + 2H₂O
From the reaction above, this is a typical neutralization process in which an acid reacts with a base to produce salt and water only.
Let's proceed; the reactant in excess is the HCl, acid. The other reactant is the Mg(OH)₂ and it must be the limiting reactant. A limiting reactant is one that is given in short supply and determines the extent of the reaction.
Find the number of moles of Mg(OH)₂;
Number of moles = 
Molar mass of Mg(OH)₂ = 24 + 2(16 + 1) = 58g/mol
Number of moles =
= 1.12moles
The balanced reaction equation shows that;
1 mole of Mg(OH)₂ gives 1 mole of MgCl₂
1.12 mole of Mg(OH)₂ will produce 1.12 moles of MgCl₂