Isopropanol is a good extraction solvent for plant pigments as it breaks down cell walls and is miscible with pigments. Can you be sure that you only extracted chlorophyll-a from your spinach leaf? If not, what else might have been extracted?

Isopropanol is a good extraction solvent for plant pigments as it breaks down cell walls and is miscible with pigments. Can you be sure that you only extracted chlorophyll-a from your spinach leaf? If not, what else might have been extracted?

Introductory Chemistry: An Active Learning Approach

6th Edition

ISBN:9781305079250

Author:Mark S. Cracolice, Ed Peters

Publisher:Mark S. Cracolice, Ed Peters

Chapter22: Biochemistry

Section: Chapter Questions

Problem 68E

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Dissolving formaldehyde in water causes the solution to contain gem-diol CH2 (OH)2. Write down the steps for the formation of formaldehyde.
Core 2 (a) The structure of limonene is shown below. CH₂ CH₂ CH₂ CH CH₂ (i) What is the molecular formula of limonene? **********‒‒‒‒‒‒‒‒‒‒‒‒‒‒‒ (II) Some limonene was added to a few drops of aqueous bromine. What colour change would you see in the aqueous bromine? ************ (iii) What feature of a limonene molecule is responsible for this colour change? (iv) Name the two substances formed when limonene is burnt in an excess of oxygen.
1) Compound 3-chlorobenzoic acid can be prepared from methylbenzene through a two- steps reaction. chemical equations for the reactions ? 2) 2 C12 (g) + 2 H20 (g) = 4 HCI (g) + 02 (g) Ac 2 HCI (g) + 1/2 02 (g) = C12 (g) + H20 (g) Ac' relationship between Ac and Ac' ? 3) Hydrogen iodide, HI decomposes 2HI (g) = H2 (g) + 12 (g) AH < 0 -2.00 atm of HI placed in a glass - allowed to reach equilibrium a) Ap for the reaction if 30.0% of HI decomposes ? b) the concentration of HI(g) will increase, decrease or remain the same when the temperature of reaction is increased ?
Methyl benzoate can be synthesized by a Fisher Esterification reaction, and then this ester can be used as a starting material in the grignard synthesis of triphenyl carbinol. Suppose that in the synthesis of methyl benzoate, a student started with 12 grams of benzoic acid and 29.86 ml of methanol. After finishing the preparation of the ester, 7.63 grams of methylbenzoate was obtained, and the benzoic acid reacted completely. What is the percent yield of the ester? ( density methanol = 0.791 g/ml, methanol = 32.04 g/mol, methyl benzoate = 136.15 g/mol, benzoic acid = 122.12 g/mol )
Write the chemical equation for the reaction of N,N-diethyl-1-propanamine with water. Which is the formula of this rule of reaction? (Hint: the amine is a base):
a) If the pH value of an aqueous solution of trimethylamine [(CH3) 3N] is 10.75, what should be the molarity of this solution? (CH3) 3N + H2O ↔ (CH3) 3NH + + OH-, Kb = 6.3 × 10-5 b) What will be the pH of the solution prepared by dissolving 8.35 g of aniline hydrochloride (C6H5NH3 + Cl-) in 750 mL of 0.215 M aniline (C6H5NH2)? Is this solution an effective buffer? Explain (Kb = 7.4 × 10-10 for aniline, C: 12.0 g / mol, H: 1.0 g / mol, N: 14.0 g / mol, Cl: 35.4 g / mol) .
Aspirin (acetylsalicylic acid, C9H8O4) is made by reacting salicylic acid (C7H6O3) with acetic anhydride [(CH3CO)2O]: C7H6O3(s) + (CH3CO)2O(l) → C9H8O4(s) + CH3COOH(l)In one preparation, 3.077 g of salicylic acid and 5.50 mL of aceticanhydride react to form 3.281 g of aspirin. (a) Which is the limitlimiting reactant (d of acetic anhydride = 1.080 g/mL)? (b) What is the percent yield of this reaction?
Aspirin (acetylsalicylic acid, C9H8O4) is made by reacting salicylic acid (C7H6O3) with acetic anhydride [(CH3CO)2O]: C7H6O3(s)+ (CH3CO)2O(l) → C9H8O4(s) + CH3COOH(l) In one preparation, 3.077 g of salicylic acid and 5.50 mL of acetic anhydride react to form 3.281 g of aspirin. (a) Which is the limiting reactant (d of acetic anhydride = 1.080 g/mL)? (b) What is the percent yield of this reaction? (c) What is the percent atom economy of this reaction?
During the lab experiment on the nitration of methyl benzoate, one of the students was able to isolate a 0.45 g of nitrated product (Methyl-3-nitrobenzene). Calculate the percent yield of the reaction from 15.12 mmol of sulfuric acid, 2.96 mmol of methyl benzoate, and 5.92 mmol of nitric acid. Hint: Methyl-3-nitrobenzene molecular weight is 181.15 g/mol. 93.3 % 83.9 % 74.6% 82.2 %
20. Suppose that you are given three colourless liquids whose identities are unknown. You are told that one is an alkane, one is an aldehyde, and one is a carboxylic acid. What property would you examine in order to differentiate between the liquids? Explain fully, using your knowledge of organic molecules and structures, how this property would allow you to distinguish between/ identify the compounds. (4A)
a) If the pH value of an aqueous solution of trimethylamine [(CH3)3N] is 10.75, what should be the molarity of this solution? (CH3)3N + H2O ↔ (CH3)3NH+ + OH-, Kb = 6,3 × 10-5 b) What will be the pH of the solution prepared by dissolving 8.35 g of aniline hydrochloride (C6H5NH3+Cl-) in 750 mL of 0.215 M aniline (C6H5NH2)? Is this solution an effective buffer? Explain (Kb = 7,4 × 10-10 for aniline, C: 12.0 g / mol, H: 1.0 g / mol, N: 14.0 g / mol, Cl: 35.4 g / mol) .
Why do impure chemicals have lowering melting points? Can recrystallization be used to purify all organic compounds?