Respuesta :
HBr reacts with LiOH and forms LiBr and H₂O as the products. The balanced reaction is
LiOH(aq) + HBr(aq) → LiBr(aq) + H₂O(l)
Molarity (M) = moles of solute (mol) / volume of the solution (L)
Molarity of LiOH = 0.205 M
Volume of LiOH = 29.15 mL = 29.15 x 10⁻³ L
Hence,
moles of LiOH = molarity x volume of the solution
= 0.205 M x 29.15 x 10⁻³ L
= 5.97575 x 10⁻³ mol
The stoichiometric ratio between LiOH and HBr is 1 : 1.
Hence,
moles of HBr in 25.0 mL = moles of LiOH added
= 5.97575 x 10⁻³ mol
Hence, molarity of HBr = 5.97575 x 10⁻³ mol / 25.00 x 10⁻³ L
= 0.23903 M
≈ 0.239 M
Hence, the molarity of the HBr is 0.239 M.
The molarity of the HBr solution is [tex]\boxed{{\text{0}}{\text{.239 M}}}[/tex] .
Further Explanation:
The concentration is the proportion of substance in the mixture. The most commonly used concentration terms are as follows:
1. Molarity (M)
2. Molality (m)
3. Mole fraction (X)
4. Parts per million (ppm)
5. Mass percent ((w/w) %)
6. Volume percent ((v/v) %)
Molarity is a concentration term that is defined as the number of moles of solute dissolved in one litre of the solution. It is denoted by M and its unit is mol/L.
The molarity equation is given by the following expression:
[tex]{{\text{M}}_{\text{1}}}{{\text{V}}_{\text{1}}} = {{\text{M}}_{\text{2}}}{{\text{V}}_{\text{2}}}[/tex]
Here,
[tex]{{\text{M}}_{\text{1}}}[/tex] is the molarity of the first solution.
[tex]{{\text{V}}_{\text{1}}}[/tex] is the volume of the first solution.
[tex]{{\text{M}}_{\text{2}}}[/tex] is the molarity of the second solution.
[tex]{{\text{V}}_{_{\text{2}}}}[/tex] is the volume of the second solution .
In the concerned question, HBr is titrated with LiOH. So molarity equation becomes,
[tex]{{\text{M}}_{{\text{HBr}}}}{{\text{V}}_{{\text{HBr}}}} = {{\text{M}}_{{\text{LiOH}}}}{{\text{V}}_{{\text{LiOH}}}}[/tex] ......(1)
Here,
[tex]{{\text{M}}_{{\text{HBr}}}}[/tex] is the molarity of the HBr solution.
[tex]{{\text{V}}_{{\text{HBr}}}}[/tex] is the volume of the HBr solution.
[tex]{{\text{M}}_{{\text{LiOH}}}}[/tex] is the molarity of the LiOH solution.
[tex]{{\text{V}}_{{\text{LiOH}}}}[/tex] is the volume of the LiOH solution.
Rearrange equation (1) to calculate [tex]{{\text{M}}_{{\text{HBr}}}}[/tex].
[tex]{{\text{M}}_{{\text{HBr}}}}=\dfrac{{{{\text{M}}_{{\text{LiOH}}}}{{\text{V}}_{{\text{LiOH}}}}}}{{{{\text{V}}_{{\text{HBr}}}}}}[/tex] ......(2)
The value of [tex]{{\text{V}}_{{\text{HBr}}}}[/tex] is 25 mL.
The value of [tex]{{\text{M}}_{{\text{LiOH}}}}[/tex] is 0.205 M.
The value of [tex]{{\text{V}}_{{\text{LiOH}}}}[/tex] is 29.15 mL.
Substitute these values in equation (2).
[tex]\begin{aligned}{{\text{M}}_{{\text{HBr}}}} &= \frac{{\left({{\text{0}}{\text{.205 M}}}\right) \times\left( {{\text{29}}{\text{.5 mL}}} \right)}}{{\left( {{\text{25 mL}}} \right)}}\\&= 0.23903{\text{ M}}\\&\approx {\text{0}}{\text{.239 M}}\\\end{aligned}[/tex]
Hence the molarity of the HBr solution is 0.239 M.
Learn more:
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Answer details:
Grade: Senior School
Subject: Chemistry
Chapter: Concentration terms
Keywords: molarity, HBr, LiOH, 0.239 M, molarity equation, volume, M1, M2, V1, V2, 25 mL, 29.5 mL, 0.205 M, concentration, concentration terms.
