Question

Determinationof ph and conductivityof soiland water sample

Answer 1

As indicated by Djamel, hydrated protons and hydroxyl ions make up a small amount of the conductivity. These small contributions mostly become relevant for pure water. Ultra-pure water has a conductivtiy of 0.055 µS.cm–1, which is determined by dissociation of pure water. Once you start changing the pH of a solution, you introduce significant concentrations of non-pH-determining ions contributing to the conductivity, hence making the relation between pH and conductivity less relevant.

You can find more info on conductivity measurements (and hence the pH measurement) in ultrapure water in the following thread. https://www.researchgate.net/post/How_can_you_determine_pH_of_high_purity_water

Answer 2

Measuring pH using litmus paper or pH strips:

Place a droplet of sample on the paper - be sure you drop or pour the sample over the paper rather than dipping the paper into the sample, as the latter may contaminate the sample.

Observe color change on the paper. If using litmus paper the paper will turn a red or pink color if the sample is acidic, while a blue paper indicates a basic sample. If using pH strips, colors corresponding to pH values should be listed on the packaging

Hope it helps you.