Question

CHM 380 Laboratory Manual Name: Lab #4: Pre-Lab Assignment Complete in advance and turn in at the beginning of class. 1. For each of the following sugars, answer the questions by filling in the table. (You may use the textbook or any other source for help on this.) Carbohydrate Is it a Reducing Sugar (has a free anomeric carbon)? Monosaccharide or Disaccharide? Aldose or ketose sugar (or both)? Glucose Fructose Sucrose Lactose 2. Based on those results, and the information in the lab, indicate whether the carbohydrate would give a positive (with a +) or negative (with a result to given test, Carbohydrate Benedict's Test Barfoed's Test Seliwanoff's Test Glucose Fructose Sucrose Lactose Copy these answers to the table on p. 39 for use in the lab

Answer 1

1)

Carbohydrate	Is it a Reducing sugar (has a free anomeric carbon)?	Monosaccharide or Disaccharide?	Aldose or Ketose sugar (or both )?
Glucose	Reducing sugar	Monosaccharide	Aldose
Fructose	Reducing sugar	Monosaccharide	Ketose
Sucrose	Non-reducing sugar	Disaccharide	Both aldose and ketose
Lactose	Reducing sugar	Disaccharide	Aldose

2)

Carbohydrate	Benedict’s Test	Barfoed’s Test	Seliwanoff’s Test
Glucose	Positive (brick red precipitate )	Positive ( scanty red precipitate)	Negative (no observation)
Fructose	Positive (brick red precipitate )	Positive ( scanty red precipitate)	Positive ( cherry red color )
Sucrose	Negative ( no color change)	Negative ( no color change)	Positive ( cherry red color )
Lactose	Positive (brick red precipitate )	Negative ( no color change)	Negative (no observation)