A beaker with 1.90×10 2 mL of an acetic acid buffer with a pH of 5.000 is sitting on a benchtop. The total molarity of acid and conjugate base in this buffer is 0.100 . A student adds 6.90 mL of a 0.300 mL solution to the beaker. How much will the pH change? The pKa of acetic acid is 4.760.
Express your answer numerically to two decimal places. Use a minus (- ) sign if the pH has decreased.