The element used in advertising signs is neon.
Answer:
-154KJ/mol
Explanation:
mole of 100ml sample of 0.2M aqueous HCl = Molarity × volume in Liter
= 0.2 × 100 / 1000 ( 1L = 1000 ml) = 0.02 mol and 0.02 mole of HCl solution require 0.02 mole of ammonia according to the mole ratio in the balanced equation.
Heat loss by the reaction = heat gain by calorimeter = mcΔT + 480 J/K
where m is the mass of water = 100g + 100g = 200g since mass of 100ml of water = 100g and it is in both of them and specific heat capacity of water 4.184 J/gK
heat gain by calorimeter = (4.184 × 200 + 480) × 2.34 = 3081.3 J
ΔH per mole = heat loss / number of mole = 3081.3 / 0.02 = 154065.6 = -154KJ/mol
The balanced chemical equation for the above reaction is as follows ;
Mg + 2HCl —> MgCl2 + H2
The stoichiometry of Mg to HCl is 1:2
This means that 1 mol of Mg reacts with 2 mol of HCl
Equal amounts of both Mg and HCl have been added. One reagent is the limiting reactant and other reactant is in excess.
Limiting reactant is the reagent that is fully used up in the reaction and the amount of Product formed depends on the amount of limiting reactant present.
In this reaction if Mg is the limiting reactant, 4.40 moles of Mg should react with 4.40x2 -8.80 moles of HCl.
But only 4.40 moles of HCl present therefore HCl is the limiting reactant that reacts with 4.40/2 = 2.20 moles of Mg
Stoichiometry of HCl to MgCl2 is 2:1
Since HCl moles reacted -4.40 mol
Then MgCl2 moles formed are 4.40/2 = 2.20 mol of MgCl2
The molarity of solution made by diluting 26.5ml of 6.0ml hno3 to a volume of 250ml is calculated using the following formula
M1V1 = M2V2, where
M1 = molality 1 (6.00m)
V1= volume 1 (26.5 ml)
M2 = molarity 2(?)
v2=volume 2 (250)
M2 = M1V1/V2
M2= 6 x26.5/250 = 0.636 M
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