Buffer 1) 100 mL of 0.50 M sodium phosphate buffer, pH 7.0 MW; 137.99

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Expert Solution

For making sodium phosphate buffer we require NaH2PO4 and solid Na2HPO4
PH = Pka + log [base/acid]
7 = 7.21 + log [base/acid]
-0.21 = log [base/acid]
10^-0.21 = base / acid = 0.6165
We shoud use 100 mL of the 0.50 M NaH₂PO₄,
and 0.030825 mole of Na₂HPO₄ in 100 mL that is 0.030825 mol / 0.1 L = 0.30825 M
so that the ratio will be 0.6165 (since base/acid = 0.6165 = 0.30825/0.50)
0.030825 mol of Na₂HPO₄ = gms / molar mass in gm/mol = gms / 141.96 gm/mol
gms of Na₂HPO₄ to be used = 0.030825 mol * 141.96gm/mol = 4.3759 gms
So, 4.3759 gms of Na₂HPO₄ must be dissolved in 100mL of solution to get a buffer with PH 7

queen_honey_blossom answered 1 year ago

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