D5w is a solution used as an intervenous fluid.it is 5.0% by mass solution of the dextrose (c6h12o6) in water. if the density of d5w is 1.029 g/ml. calculate the molarity of the dextrose in the solution.

0.29 mol/L

Explanation:

Its density is 1.029 g/ml so in a liter (1000 mL) there is 1029 g of solution, but only 5% is dextrose.

0.05x1029=51.45

So in a liter of D5W solution there is 51.45 g of dextrose.

Dextrose molar mass iss 180.156 g/mol, so in 51.45 g of dextrose there is

51.45/180.156=0.29 mol

In one liter of solution there is 0.29 mol of dextrose, so the molarity of such solution is 0.29 mol/L.

−−−−−−−−−−−−−−

Zn2+(aq)+2e⇌Zn(s)××××x−0.76

Cu2+(aq)+2e⇌Cu(s)××××x+0.34

×××××××××××−−−−−−−−−−−−−−−→

The 1/2 cell with the most +ve E∘ value will take in the electrons.

So we can see that the copper 1/2 cell will be driven left to right and the zinc 1/2 cell right to left as indicated by the arrows.

So the two 1/2 equations are:

Zn(aq)→Zn2+(aq)+2e

Cu2+(aq)+2e→Cu(s)

Adding these gives the cell reaction when it is working:

Zn(s)+Cu2+(aq)→Zn2+(aq)+Cu(s)

When the zinc atoms lose electrons the zinc ions go into solution and the 2 electrons flow away from this electrode into the external circuit.

When they arrive at the copper electrode, they are picked up by the copper(II) ions to become copper atoms.

The two 1/2 cells are connected by a salt bridge or a membrane. The salt bridge consists of some filter paper soaked in a suitable electrolyte such as saturated potassium nitrate solution.

The function of the salt bridge is to maintain electrical neutrality in each half cell.

As zinc ions go into solution NO−3 ions flood in to the half cell.

As copper(II) ions leave the solution in the other 1/2 cell, K+ ions flood in.

To find the emf of the cell, subtract the least +ve E∘ value from the most +ve:

E∘cell=+0.34−(−0.76)=+1.1V

This arrangement is known as "The Daniel Cell".