Formula for sodium hydrogen carbonate nahco3? or na2hco3?

The kw for water at 0 °c is 0.12× 10–14 m2. calculate the ph of a neutral aqueous solution at 0 °c.

A155.0 9 piece of copper at 182 °c is dropped into 2500 g of water at 23.9 °c. (the specific heat of copper is 0.385 1/9°c.) calculate the final temperature of the mixture. (assume no heat loss to the surroundings.)

How do you interpret a chromatogram for what mixtures contain?