Calculate the ph of a buffer consisting of 0.50 m hf and 0.45 f- a) before b) after addition of 0.40 g of naoh to 1.0 l of the buffer

201cm/s÷5: 18

explanation:

there is no explanation

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.