<|system|>
Calculate the Debye-Hückel screening length $1 / \kappa$ at $298 \mathrm{~K}$ in a $0.0075 \mathrm{~m}$ solution of $\mathrm{K}_3 \mathrm{PO}_4$.</s>.
<|user|>
Can you answer based on context?
<|assistant|>
1.4