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Acid-base theory

Buffers

Exercise 1

   

The following reagents were mixed. Indicate in which case we end up with a buffer and why!

a) $50 \;mL$ $CH_3COOH$ 0.050 M and $50 \;mL$ $CH_3COONa$ $0.05\; M$

Buffer

b) $50 \;mL$ $CH_3COOH$ $0.050\; M$ and $50 \;mL$ $NaOH$ $0.10\; M$

Excess $NaOH$ : no buffer

c) $50 \;mL$ $CH_3COOH$ $0.050\; M$ and $50 \;mL$ $NaOH$ $0.010\; M$

Buffer (all $NaOH$ reacts to give sodium acetate, some acetic acid remains )

d) $1 \;L$ $H Cl$ $0.050\; M$ and $6.80\; g$ pure $HCOONa$

Buffer (all $HCl$ reacts to give formic acid, there remains some formiate )

e) $1 \;L$ $H Cl$ $0.050\; M$ and $4.40\; g$ pure $HCOOH$

No buffer (two acids)