Lấy 5ml dd hồ tinh bột vào ông nghiệm, thêm 4 giọt dd H2SO4 10%. Lắc kỹ, đun sôi 20 phút. cứ mỗi 5 phút lấy ra 5 giọt dd đnag đun cho vào ống nghiệm khác nhau. Để nguội, nhỏ 1-2 giọt dd iod. Quan sát, nhận xét, giải thích. Đến khi dd kong có màu với dd iod nữa thì ngừng đun. Để nguội, lấy 5 giọt dd thủy phân vào ống nghiệm. Trung hòa bằng NaOH , kểm tra bàng giấy quỳ. Thêm 5 giọt thuốc thử Fehling, lăc kỹ, đun cách thủy sôi nhẹ 5-7 phút. Quan sát, nhận xét, giải thích

Which of the following contributes to the structural rigidity of cellulose? adjacent glucose polymers are stabilized by hydrogen bonding. glucose residues are joined by (α1→4) linkages. cellulose is a highly branched molecule. the conformation of the glucose polymer is a coiled structure.

Achemistry student needs to standardize a fresh solution of sodium hydroxide. he carefully weighs out of oxalic acid , a diprotic acid that can be purchased inexpensively in high purity, and dissolves it in of distilled water. the student then titrates the oxalic acid solution with his sodium hydroxide solution. when the titration reaches the equivalence point, the student finds he has used of sodium hydroxide solution.calculate the molarity of the student's sodium hydroxide solution. be sure your answer has the correct number of significant digits.

Air can be considered a mixture. which statement does not explain why?