5.50 x 10^-3 mol

Step-by-step explanation

For a buffer to reach its maximum buffer capacity (a measure of how effective a buffer is), the amount of its conjugate base must be equal to the amount of the weak acid. In the case of acetate buffer, the amount of sodium acetate trihydrate must be equal to the amount of acetic acid.

amount of total buffer = amount of sodium acetate trihydrate + amount of acetic acid

n_{total buffer} = n_{sodium acetate trihydrate} + n_{acetic acid}

Because n_{sodium acetate trihydrate} = n_{acetic acid} for maximum buffer capacity,

n_{total buffer} = 2 n_{sodium acetate trihydrate}

The n_{total buffer} can be determined by multiplying the molarity (in mol/L) of the buffer by its volume (in L). 

n_{total buffer} = M_buffer x V_buffer = 0.110 mol/L x 0.1000 L = 0.0110 mol

Use the calculated n_{total buffer} to solve for n_{sodium acetate trihydrate}.

n_{total buffer} = 2 n_{sodium acetate trihydrate}

n_{sodium acetate trihydrate} = n_{total buffer} / 2 = 0.0110 mol / 2 = 5.50 x 10^-3 mol