[glaceon97]

Have to hang it in on Wed so I am really appreciate if anyone can tell me how to answer them.

We dissolve sucrose in water and have 250 mL. We put 25.0 ml of sucrose into each beaker, and there are 7 of them. solution #0 is in room temp and no HCl, the other 6 are in hot water and has HCl and converted to fructose and glucose.

Qs: Finding the initial mass of sucrose in each of the solution. Suppose you are asked to produce a mixture of three sugars where 67% sucrose has been converted, at what point should the reaction be stopped?

This is my data:
Mass of sucrose: 50.094g
Time & Temp:
 5 mins = 65.1
10 = 63.5
15 = 63.5
20 = 63.2
25 = 63.2
30 = 63.2
Optical Rotation:
0: +6.05
1: +4.05
2: +3.90
3: - 0.40
4: -1.05
5: -1.35
6: -1.55

[Borek]

You have to show your attempts at solving the problem to receive help, this is a forum policy.

[orthoformate]

https://en.wikipedia.org/wiki/Specific_rotation

This website should help you. Once you put up an attempt, we can start helping. This is a very interesting question.

[glaceon97]

Sorry, I had no clue first so I did not have an attemp. After seeing your website I got a clue and did it, but I'm not sure about:

Solution 1:
66.05°= +4.05/1.00 x c => c = 0.0609 g/mL
initial mass sucrose: 0.0609 x 25.0 mL = 1.52g

For the later question, just saw that they want me to do the graph and point it out so no worry. Thanks.

[Arkcon]

OK, try this one:  You have a plate of 12 donuts.  Every ten minutes, you eat one.  How long before you only have six donuts?

TH is is essentially the question before you.  Except you're not counting sweets, but detecting them by their ability to rotate the plane of polarized light.  Your textbook or class notes should be able to help you with the definition of optical rotation, and what's going to happen as sucrose becomes fructose and glucose, and its up to you to build the correlation.

Looking at it another way.  If sucrose was blue in color, and glucose ad fructose were yellow in color, you'd know what the beginning and ending would look like, but what about 10% converted, 50% converted, or the elusive 67% -- they'd all be different shades of green.  That's what you'd be looking for.

Unfortunately, we can't see the plane of polarized light.  But once we have a machine that can, and it spits out a number, the task is the same.

[orthoformate]

Here's another hint:

We know from the website that sucrose has a [α]=+66.3 at 1g/100 mL

In the current experiment, we know that we have [α]=+6.05 at 1g/10 mL
(you wrote 25 mL...but I think you meant grams?)

We know based on the formula [α]=α/(l*c) that  [α] should decrease as c increases (α and l are constant).

neglecting the rotation effects of glucose and fructose, how could we plot this?

How could we plot this if we consider the rotational effects of fructose and glucose?

[orthoformate]

Here's another hint:

We know from the website that sucrose has a [α]=+66.3 at 1g/100 mL

In the current experiment, we know that we have [α]=+6.05 at 1g/10 mL
(you wrote 25 mL...but I think you meant grams?)

We know based on the formula [α]=α/(l*c) that  [α] should decrease as c increases (α and l are constant).

neglecting the rotation effects of glucose and fructose, how could we plot this?

How could we plot this if we consider the rotational effects of fructose and glucose?

please disregard this, it is horribly wrong.

[orthoformate]

When you say 25mL of sucrose...did you mean 25 g?

using the formula [α]= α/l*c

+66.33 = +6.05/l*0.158

l= 0.58 dm

is this correct?