A _____ (released, absorbed, taken, +,-) ΔH means that energy is______ (released, absorbed, taken, +,-) from a reaction.
2 answers:
<u>Answer:</u> The blanks are completed below.
<u>Explanation:</u>
Enthalpy change of the reaction is defined as the difference in the potential energy of the products and the potential energy of the reactants. It is represented as
Mathematically,
When of the reaction is negative, then potential energy of the products is less than the potential energy of the reactants. So, energy is being released.
Thus, a +ve means that energy is released from a reaction.
When of the reaction is positive, then potential energy of the products is more than the potential energy of the reactants. So, energy is being absorbed.
Thus, a -ve means that energy is absorbed from a reaction.
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Answer:
6.69%
Explanation:
Given that:
Mass of the fertilizer = 0.568 g
The mass of HCl used in titration (45.2 mL of 0.192 M)
=
= 0.313 g HCl
The amount of NaOH used for the titration of excess HCl (42.4 mL of 0.133M)
=
= 0.0058919 mole of NaOH
From the neutralization reaction; number of moles of HCl is equal with the number of moles of NaOH is needed to complete the neutralization process
Thus; amount of HCl neutralized by 0.0058919 mole of NaOH = 0.0058919 × 36.5 g
= 0.2151 g HCl
From above ; the total amount of HCl used = 0.313 g
The total amount that is used for complete neutralization = 0.2151 g
∴ The amount of HCl reacted with NH₃ = (0.313 - 0.2151)g
= 0.0979 g
We all know that 1 mole of NH₃ = 17.0 g , which requires 1 mole of HCl = 36.5 g
Now; the amount of HCl neutralized by 0.0979 HCl =
= 0.0456 g
Therefore, the mass of nitrogen present in the fertilizer is:
=
= 0.038 g
∴ Mass percentage of Nitrogen in the fertilizer = %
= 6.69%