Question

+. Calculate the molarity of a solution containing 7.50 mol formaldehyde, CH20, in enough water to make 1.50 L of solution. 2. Calculate the molarity of 50.0 mL of solution containing 7.50 g of methanol, CHO. 3. Calculate the number of moles and grams of ethyl alcohol, C2H60, in 29.21 mL of a 6.013 M solution. Dilution: 4. Calculate the final concentration of NaCl after 1.25 L of 0.500 M NaCl is (a) diluted to 2.50 L with water and (b) diluted by the addition of 2.50 L of water.

Answer 1

1) 2) mole of formaldehyde = 7.5 mol volume of solution = 15L oma so, molarity of formaldehyde- mole volume Lin L) Pero 7.5 mol 1.5 L Mzoda SM ld woh to nortortres no mass of methanol = 7.59 32541 - omulou Call me Mw of CH4O = 32g/mol mol of CHUO - Given mass nortulb Ni tort worst Mw 7.59 1 32 g/mol gialad stulor to dow volume of Solutions 50 mt = 0.05L ... molarity of methanol a mol volume LinL) 745 mol Contoh 32xooosh = 4:6875 M

3 molarity of ethyl alcohol = 6.013 M Volume of ethyl alcohol solution 29.21 ml 2 50-02921 L . mol of ethyl alcohol - molarity & volume LinL) - 6.013M X 0.029 21 L = 0.17564 mol O mass of ethyl alcohol = molex Mw - 017564 molx 46 g/molt nobno 8.079449 ~ 8.089 4) concentration of NaCl before diution = 0.5M Initial volume = 1.251 final volume = 2.5L We know that in dilution moles of solute remains the same even after dilution So, mole of solute before dilution = mole of solute after dilution » Molarityeimitied) Volume initial) – Molaring e finale) * Volumel final) - 0.5M X 1.25L - Molarity (final) X 2.52 loro 0.5 MX d.25L . Molarity (final) : 2:52 0.25m

now, So dilution is done by adding 2.5L of water it final volume of solution 1.252 +2.5L o se = 3.75L 2 so, M (final) Menitid) x V initial) de tulisi - V (final) du bade lasting mos Sort 0.5M X 1.2514 3.75L Wer evitar sa srod 2 0.166671%