A 35.0 ml sample of 0.225 M HBr was titrated with 42.3 ml of KOH. What is the concentration of the KOH?
vol x molarity = vol x molarity
molarity of KOH = 35/42.3 x .225 M = 0.186 M, the first option.
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To determine the concentration of KOH, we can use the stoichiometry of the reaction between HBr and KOH. The balanced equation for the reaction is:
HBr + KOH → KBr + H2O
From the balanced equation, we can see that the mole ratio between HBr and KOH is 1:1. This means that the number of moles of KOH used in the reaction is equal to the number of moles of HBr.
First, let's calculate the number of moles of HBr:
moles of HBr = volume of HBr solution (in liters) × concentration of HBr (in moles/liter)
Given: volume of HBr solution = 35.0 ml = 0.035 L
Given: concentration of HBr = 0.225 M
moles of HBr = 0.035 L × 0.225 moles/L
moles of HBr = 0.007875 moles
Since the stoichiometry of the reaction is 1:1, the number of moles of KOH used in the reaction is also 0.007875 moles.
Next, let's calculate the concentration of KOH:
concentration of KOH = moles of KOH / volume of KOH solution (in liters)
Given: volume of KOH solution = 42.3 ml = 0.0423 L
concentration of KOH = 0.007875 moles / 0.0423 L
concentration of KOH ≈ 0.186 M
Therefore, the concentration of the KOH solution is approximately 0.186 M.
To find the concentration of KOH (potassium hydroxide), you can use the equation for a balanced chemical reaction between HBr (hydrobromic acid) and KOH. The balanced equation is:
HBr + KOH → KBr + H2O
Applying the principle of stoichiometry, the ratio of moles between HBr and KOH is 1:1. Therefore, the moles of HBr reacted will be equal to the moles of KOH added.
To begin, we need to determine the number of moles of HBr initially present in the 35.0 mL sample. To do this, we can use the formula:
moles = concentration (M) x volume (L)
Converting the volume to liters:
35.0 ml = 35.0 ml * (1 L / 1000 ml) = 0.035 L
Now we can calculate the moles of HBr:
moles of HBr = concentration of HBr x volume of HBr
moles of HBr = 0.225 M x 0.035 L
Next, we need to determine the concentration of KOH by comparing the moles of KOH and the volume of KOH. According to the balanced equation, the ratio of moles between HBr and KOH is 1:1:
moles of KOH = moles of HBr
Finally, we need to convert the volume of KOH to liters.
42.3 ml = 42.3 ml * (1 L / 1000 ml) = 0.0423 L
Now, we can calculate the concentration of KOH:
concentration of KOH = moles of KOH / volume of KOH
concentration of KOH = moles of HBr / volume of KOH