-A sample consist 90% NaOH and 10% CaO,whats the concentration of NaOH in the solution of this 3g sample,dissolved in 250cm3.

-How many cm3 of H2SO4 with concentration of 0.255M are needed for titration of 100cm3 of this solution

amount NaOH = 3*0.9 = 2.7g

amount CaO = 3*0.10 = 0.3 g

mols NaOH = 2.7g/molar mass NaOH.
mols CaO = 0.3 g/molar mass CaO.

M NaOH = mols NaOH/0.250L
M CaO = mols CaO/0.250L

For the titration.
mols CaO = M x L = ?
mols NaOH = M x L = ?

Set up equations for the titration with H2SO4, solve for cc H2SO4 for NaOH and cc H2SO4 for CaO, then add cc H2SO4 to total. Post your work if you get stuck.

To find the concentration of NaOH in the solution:

Step 1: Determine the amount of NaOH in the sample.
3 grams x 0.9 = 2.7 grams of NaOH.

Step 2: Convert the mass of NaOH to moles.
2.7 grams NaOH / 40 g/mol = 0.0675 moles of NaOH.

Step 3: Convert the volume from cm3 to liters.
250 cm3 = 0.25 liters.

Step 4: Calculate the concentration of NaOH.
Concentration (M) = moles / volume (L)
Concentration (M) = 0.0675 moles / 0.25 L ≈ 0.27 M

Therefore, the concentration of NaOH in the solution is approximately 0.27 M.

To find the amount of H2SO4 needed for titration:

Step 1: Calculate the moles of NaOH in 100 cm3 of the solution.
Concentration (M) = moles / volume (L)
0.27 M = moles / 0.1 L
Moles of NaOH = 0.27 M x 0.1 L = 0.027 moles.

Step 2: Use the balanced equation of the reaction between NaOH and H2SO4 (assuming 1:1 ratio) to find the moles of H2SO4 needed.
1 mole of NaOH reacts with 1 mole of H2SO4.

Step 3: Calculate the volume of H2SO4 needed in liters.
Moles of H2SO4 needed = 0.027 moles.
Volume of H2SO4 (L) = moles of H2SO4 / concentration (M)
Volume of H2SO4 (L) = 0.027 moles / 0.255 M ≈ 0.106 L.

Step 4: Convert the volume of H2SO4 to cm3.
Volume of H2SO4 (cm3) = 0.106 L x 1000 cm3/L ≈ 106 cm3.

Therefore, approximately 106 cm3 of H2SO4 with a concentration of 0.255 M are needed for the titration of 100 cm3 of the NaOH solution.

To find the concentration of NaOH in the solution, you need to consider the ratio of NaOH in the sample.

1. Calculate the mass of NaOH in the sample:
Mass of NaOH = 90% of 3g = 0.9 * 3g = 2.7g

2. Convert the mass of NaOH to moles:
Moles of NaOH = Mass of NaOH / Molar mass of NaOH
The molar mass of NaOH = 23g/mol + 16g/mol + 1g/mol = 40g/mol
Moles of NaOH = 2.7g / 40g/mol = 0.0675 mol

3. Calculate the volume of the solution in liters:
Volume of solution = 250 cm3 = 250 mL = 250/1000 L = 0.25 L

4. Calculate the concentration of NaOH in the solution:
Concentration (C) = Moles / Volume
Concentration of NaOH = 0.0675 mol / 0.25 L = 0.27 mol/L

Therefore, the concentration of NaOH in the solution is 0.27 mol/L.

Now, let's move on to the second question.

To calculate the volume of H2SO4 needed for titration, you need to use the concept of stoichiometry and the balanced equation between NaOH and H2SO4.

The balanced equation for the reaction between NaOH and H2SO4 is:
2 NaOH + H2SO4 -> Na2SO4 + 2 H2O

From the equation, we can see that it takes two moles of NaOH to react with one mole of H2SO4.

1. Calculate the moles of NaOH that reacted in the 100mL (0.1L) of the solution:
Moles of NaOH = Concentration of NaOH * Volume of solution
Moles of NaOH = 0.27 mol/L * 0.1 L = 0.027 mol

2. Since two moles of NaOH react with one mole of H2SO4, the moles of H2SO4 needed are the same as moles of NaOH:
Moles of H2SO4 = 0.027 mol

3. Calculate the volume of 0.255M H2SO4 needed to react with the calculated moles of H2SO4:
Volume of H2SO4 = Moles of H2SO4 / Concentration of H2SO4
Volume of H2SO4 = 0.027 mol / 0.255 mol/L = 0.106 L

Finally, convert the volume from liters to cubic centimeters (cm3):
Volume of H2SO4 = 0.106 L * 1000 cm3/L = 106 cm3

Therefore, you would need 106 cm3 of H2SO4 with a concentration of 0.255M for the titration of 100 cm3 of the NaOH-CaO solution.