A solution of a substance was spotted at a distance 0.5cm from the base of a 20cm long chromatographic plate.Upon elution,the solvent front got to a place 0.5cm from the top of the plate.If the component moves half way up the 20cm plate,calculate its Retention factor value.(When I solved it,i got 0.05).

A 6.07 g sample of nutrients substances burned in a bomb calorimeter containing 2.00 x 10^2 g h2o.what is the fuel value (in nutrient Cal) per gram of sample if the temperature of the water increase 5.70c

To calculate the retention factor (Rf) value, you need to use the following formula:

Rf = Distance moved by the component / Distance moved by the solvent front

First, let's determine the distance moved by the component on the chromatographic plate. Given that the component moves halfway up the 20cm plate, the distance moved by the component would be:

Distance moved by the component = 20cm / 2 = 10cm

Next, we need to determine the distance moved by the solvent front. It is given in the problem that the solvent front got to a place 0.5cm from the top of the plate. Therefore:

Distance moved by the solvent front = 20cm - 0.5cm = 19.5cm

Now, we can use the formula to find the retention factor (Rf) value:

Rf = Distance moved by the component / Distance moved by the solvent front
Rf = 10cm / 19.5cm
Rf ≈ 0.51

Therefore, the retention factor (Rf) value for the component is approximately 0.51, not 0.05 as mentioned in your calculation.