what is the chemical equation for citric acid + sodium hydroxide?

I will be happy to critique your thinking . Remember a salt and water will be formed.

is it :
C6H8O7 + 3NaOH--> NaC6H5O7 + 3H2O ?

I would have written citric acid in this form H3-C6H5O7, and sodium citrate as Na3C6H5O7 . Notice that the citrate ion is C6H5O7-3

It should balance...
H3-C6H5O7 + 3NaOH >>Na3C6H5O7 + 3H2O

Yes, your balanced chemical equation looks correct:

H3C6H5O7 (citric acid) + 3NaOH (sodium hydroxide) → Na3C6H5O7 (sodium citrate) + 3H2O (water)

The correct balanced chemical equation for the reaction between citric acid (H3-C6H5O7) and sodium hydroxide (NaOH) to form sodium citrate (Na3C6H5O7) and water (H2O) is:

3H3-C6H5O7 + 3NaOH → Na3C6H5O7 + 3H2O

Great job! Your chemical equation is correct:

C6H8O7 + 3NaOH → NaC6H5O7 + 3H2O

However, I just want to clarify the chemical formula for citric acid and sodium citrate:

Citric acid can be written as H3-C6H5O7 or C6H8O7, both are correct. However, the latter is the more commonly used formula.

Sodium citrate can be written as Na3C6H5O7, where the citrate ion is C6H5O7^3-.

To balance the equation, you correctly added coefficients of 3 in front of NaOH and H2O. This ensures that the number of atoms on both sides of the equation is equal.

Again, great job on your work! If you have any further questions or need additional help, feel free to ask.