## chemistry calculations help

any help with the below probs will be appreciated

1) To determine the optimal dilution of fluorescent dye DAPI, you prepare a titration series with 0.3 ug/ml, 1 ug/ml, 3 ug/ml, 10 ug/ml och 30 ug/ml DAPI in a buffer and test it on tissue samples. You need 1 ml of every dilution and stock solution (0.1 mg/ml) you can use for the purpose. How much DAPI do you add to each test tube.
2) It is covinient to have ready prepared stock solutions of reagents you use frequently in the lab, how much do you measure to prepare the following solutions?
a) 0.5 Tris (MW: 121.1 g/mol), 0.21
b) 50 mM EDTA (MW: 372.2 g/mol), 200 ml
3) You want to make 21 of 137mM NaCl. As you need it quite often you start by making a 2M stock solution.
a) How much NaCl (MW = 58.44) do ou measure for 11 stock solution?
b) How much of the stock solution do you use for dilution?
4) You are about to prepare 250ml of a buffer with pH 7.4 containing;

134 mM NaCl stock concentration: 5 M
12 mM NaCO3 stock concentration: 0.5M
2.9 mM KCL stock concentration: 2.5 M
0.34 mM NaH2P04 stock concentration: 100 mM of NaH2PO4*H20
5 mM HEPES stock concentration: 0.1 M
5 mM GLUKOS stock concentration: 0.25 M

As you use this buffer frequently you have stock solutions of ingredients. However, you notice that you have run out of the following stock solutions: NaCl (MW = 58.44), KCL (MW=74.56) and NaH2PO4*H20 (MW=137.99, note that the final buffer is without crystal water). How much of these reagents do you need to make the following amounts of stock solutions?
a) 50 ml Nacl
b) 10 ml KCL
c) 10 ml NaH2PO4*H20

How much do you need of the stock solutions to make 250 ml buffer?

You measure the pH of your prepared buffer. The pH is 7.1, what do you do?
5) You have a bottle containing 1M MgS04*7H20 on your shelf. The molecular weight of MgSO4*7H20 is 246.48. You need 100 ml of a 20 mM MgSO4 solution. How do you make it?

What is the concentration of MgS04 in the solution in % (w/v)?

6) You have measured 44.50 g Na2HPO4*2H2O (MW 177.99) and have dissolved it in 1 litre of water. Unexpectedly, you need a Na2HPO4 solution at the concentration 25mM and notice that the chemical bottle is empty. You have your experiments prepared and need to continue A.S.A.P. what do you do ( you cannot borrow it from anybody else) ?.
7) You need 100 ml of a solution containing 0.5 % (w/v) glucose (MW: 180.16). how do you prepare it if you use
a) solid glucose or
b) 0.2 M glucose stock solution?
8) you need 200 ml of solution with 10% (v/v) glycerol in PBS (phosphate buffered saline). You have 80% (v/v) glycerol and 10 x PBS. How do you proceed?
1) To make a DNA protein binding reaction, you need a buffer containing;
2mM EDTA
20mM Tris
100mM NaCl
10 % (v/v) glycerol

You have;

50mM EDTA
0.5M Tris
80% (v/v) glycerol

You need 100ml buffer. How do you prepare it?1) To make a DNA protein binding reaction, you need a buffer containing;
2mM EDTA
20mM Tris
100mM NaCl
10 % (v/v) glycerol

You have;

50mM EDTA
0.5M Tris
80% (v/v) glycerol

1) You need 100ml buffer. How do you prepare it?

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