Question

give four steps of procedure to set up an experiment to establish the relationship between the loss of weight of solid when fully immersed in (i)tap water(ii) Salty water and weight of water displaced by it

Answer 1

We’ll first prepare the strong salty water:

Take 400 ml of tap water in a 500 ml beaker, add some common salt to it and stir well. Go on adding salt to the water and dissolve it by stirring the solution with a glass rod until some of the salt remains undissolved in the beaker. Decant the strong (saturated) salty water and store for further use.

Now to start:

Hang a spring balance on an iron stand using a clamp.

Note the least count of the spring balance.

Take one of the solid blocks (S1) and weigh it by hanging it on the hook of the spring balance using a thread. Find the weight of the solid in air (Wa) and note it.

Take two beakers (each of 250 ml) and mark them as A and B. Weigh them on a balance separately and note down the mass of beaker A and B.

Take an overflow can and fill it with water to the brim of the outlet and place beaker A below the overflow outlet of the can to collect the displaced water. Now, start lowering the metallic block (S1), still attached to the spring balance into the water of the overflow can.

Note the loss of weight of the metallic block as it gets completely immersed in the water. Weigh beaker A which contains the displaced water and note the mass. To find the mass of the water displaced, subtract the initial mass of beaker A (without displaced water) from the present mass of the beaker A (containing displaced water).
Repeat the experiment using the metallic block S1 by completely immersing it in the strong salty water in the overflow can. Note the loss in weight S1 by immersing it in the strong salt solution. Find the mass of the salt solution displaced and collected in the beaker
As done using the simulator:

From the combo box, Select Environment, select the place where the experiment to be carried out.

Note down the least count of the spring balance.

The experimental blocks (Iron and Copper) are provided in the simulator window. It can be attached to the spring balance by double clicking on it.

The simulation can be performed in three media: air, tap water or salty water.  To do this, choose any one of the above media from the drop down box under ‘Loss of weight’.

You can now find the weight of the block by moving the mouse over the scale of the spring balance.  This shows a zoomed in area of the scale that aids in taking the reading easily.

You can choose the medium as tap water or salty water  for immersing the object.

From the digital balance, note the mass of the empty beaker.

Again as before, select the object of your choice and find the weight after immersing the block in solution.

Now, the liquid overflows. Note down the new mass displayed in the digital balance.

The ‘Reset’ button can be used to reset the experiment to its initial state.

 

Observations:

Weight of metallic block S1 in air = .................. g wt.

Mass of empty beaker = ............ g.

Weight of the block (S1) after  immersed in solution = ................. g wt.

New mass displayed in the digital balance = ................. g.

Loss of weight of block in air = .............. g wt.

Mass of water displaced (m) = ...................... g.

Weight of solution displaced = m x g = ............ g wt. 

Least count of the spring balance :

                        5 divisions = 25 g.wt

                        1 division = 25/5

                                           =5 g.wt

Precautions:

1.   The string used to hang the spring balance should have negligible weight.

2.   The metallic block should be gradually immersed in water.

3.   Reading of spring balance should be taken only when it is stable.

4.   When immersing the metallic block in water, care should be taken that displaced water does not spill.