if 30.0 ml of 0.500 m KOH are needed to neutralize 10.0 mL of H2SO4 of unknown concentration what is the molarity of the sulfuric

Question

please help i dont understand

Answer 1

Write out the balanced chemical equation:

H₂SO₄ + 2KOH → K₂SO₄ + 2H₂O

As seen in our balanced chemical equation, the molar ratio of sulfuric acid and potassium hydroxide is 1:2. Thus, for every 1 mol of H₂SO₄, we will need 2 mol of KOH to neutralize it:

30.0 mL KOH x (1 L KOH/1000 mL KOH) x (0.500 mol KOH/L KOH) x (1 mol H₂SO₄/2 mol KOH) =

0.0075 mol H₂SO₄

0.0075 mol H₂SO₄ x (1/10.0 mL H₂SO₄) x (1000 mL H₂SO₄/1 L H₂SO₄) =

0.75 M H₂SO₄

Answer 2

Step 1: Write the unbalanced chemical reaction equation from the word problem (for acids base reactions this is often a double replacement reaction so switch the cations to get the products):

KOH + H₂SO₄ → KSO₄ + H₂O

Step 2: Balance the individual compounds for charge (products only since the reactants were given)

SO₄ has a -2 charge and K has a +1 charge so we need 2 K atoms to balance the charge so it should be K₂SO₄

KOH + H₂SO₄ → K₂SO₄ + H₂O

Step 3: Balance the equation by adjusting the mole ratios (coefficients)

There needs to be 2 K's on the left to match the 2 K's on the right so make it 2KOH. That means we now have 4 H's on the left and only 2 H's on the right so I need to make it 2H₂O on the right.

2KOH + H₂SO₄ → K₂SO₄ + 2H₂O

Step 4: Draw a roadmap based on the word problem of where we start to where we are going:

Step 5: Start with Givens and, using the roadmap convert through to the products making sure the units cancel and transform properly (write M values as moles/Liter)

After canceling units, the only units left is moles H₂SO₄ per Liter of H₂SO₄ - that is the same as molarity or M.

Step 6: Multiply the numbers on the top and divide by the numbers on the bottom:

0.5 x 1 x 30 x 1 x 1000 / 1 / 1000 / 2 / 10 / 1 = 0.75 M H₂SO₄