Calculate the [H+] for: black coffee with a pH of 6.9 (Enter your answer as follows: 1.0E-2 for 0.010)

[H+] =antilog(-pH)=10^-6.9

= 1.26e-7

To calculate the [H+] for black coffee with a pH of 6.9, you can use the equation:

[H+] = 10^(-pH)

In this case, the pH is 6.9, so the equation becomes:

[H+] = 10^(-6.9)

To solve this, you can use a scientific calculator or an online calculator.

By plugging in the values and solving the equation, you will find that the [H+] concentration for black coffee with a pH of 6.9 is approximately 1.0E-7 (or 0.0000001).

So, the [H+] for black coffee is 1.0E-7.