Exp 1 - 1 mL of ice-cold water to help transfer. 6. Weigh...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
TA: HSIEN-PO CHIU Sep 18 & 20, 2007 Exp 1. Learning Basic Operations Principles: A. The effect of pH on Sodium Benzoate 1. Reaction O ONa + HCl O OH + NaCl 2. Organic acids usually are weak acids which have partial dissociation of protons. 3. Organic acids have lower solubilities in water than organic acid salts. So organic acids may crystallize in water and can be separated from the solution by filtration. B. Measuring the density of an unknown liquid Density = Mass / Volume Procedures: A. The effect of pH on Sodium Benzoate 1. Add 0.4 g of sodium benzoate to a 5 mL conical vial. 2. Add 3 mL water into the conical vial and stir the solution by glass rod until the sodium benzoate dissolves. 3. Add 3 M HCl (aq) into the solution with stirring, check pH of solution by pH paper, keep adding HCl until pH ~ 2 4. Cool the solution by ice-water bath 5. Filtrate the benzoic acid by vacuum filtration [OP-13] with a Hirsch funnel. Use ~
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1 mL of ice-cold water to help transfer. 6. Weigh the benzoic acid crystals B. Measuring the density of an unknown liquid 1. Take a 10 mL graduate cylinder on a balance, record the tare weight of cylinder. 2. Add 0.5 mL of unknown liquid each time in that graduate cylinder and record the weight each time until 2.5 mL. Advanced Results: A. The effect of pH on Sodium Benzoate 1. Theoretical yield (g) 2. Purification yield (%) B. Measuring the density of an unknown liquid Do the x-y plot to express the relationships between mass and volume. Figure out the density of your unknown liquid. Q&A 1. Sodium benzoate was treated with hydrochloric acid to produce a solid precipitate named (A) sodium chloride (B) benzene (C) benzoic acid (D) sodium benzoate 2. To calculate the density of unknown liquid using x-y plot, the x-axis will be (A) mass (B) volume (C) density (D) viscosity if the slope is the density...
View Full Document

Ask a homework question - tutors are online