Question #5cff2

1 Answer
Jun 4, 2017

Answer:

#1.153x10^-3gram Na_2CO_3#

Explanation:

#5L(0.004M Ca^+2) + ? max grams(Na_2CO_3) => no .pptn.#

#CaCO_3 rightleftharpoons Ca^(+2) + CO_2^-2#
#K_(sp)=[Ca^(+2)][CO_3^(-2)] = 8.7x10^(-9)#
#[Ca^(+2)]=0.004M#

=> #(0.004M)[CO_3^(-2)] = 8.7X10^(-9)#

=> #[CO_3^(-2)]= (8.7x10^(-9)"/0.004")M = 2.175x10^(-6)M#

=> #Na_2CO_3 => 2Na^+ + CO_3^(-2)#
#>##f.wt.(Na_2CO_3)= "106g"/"mole"#
#Na_2CO_3(g/L)= 2.175x10^(-6)"mole"/L*106g/"mole" = 2.31x10^(-4)g/L#

=>
#"max.""mass"Na_2CO_3 ".for" .5L(0.004M Ca^(+2)) = 5L(2.31x10^(-4)g/L) = 1.153x10^(-3)grams Na_2CO_3#