How you would make 100.0 ml of a 1.00 mol/L buffer solution with a pH of 10.80 to be made using only sodium carbonate, sodium hydrogen carbonate and water? How much sodium carbonate and sodium hydrogen carbonate would you use?

Answer 1

You would add 7.96 g of sodium carbonate and 2.09 g of sodium hydrogen carbonate to a volumetric flask and then add enough water to make the volume up to 100.0 mL.

This question is like the question in

https://tutor.hix.ai

1. Calculate the concentration ratios

The chemical equation for the equilibrium is

HCO₃⁻ + H₂O ⇌ CO₃²⁻ + H₃O⁺; #K_"a"# = 4.8 × 10⁻¹¹; #pK_"a"# = 10.32
HA + H₂O ⇌ A⁻ + H₃O⁺

The Henderson-Hasselbalch equation is

pH = #pK_"a" + log(([A⁻])/([HA]))#

10.80 = 10.32 + # log(([A⁻])/([HA]))#

#log(([A⁻])/([HA]))# = 10.80 – 10.32 = 0.48

#([A⁻])/([HA]) = 10^0.48# = 3.02 (3 significant figures)

This makes sense. pH > #pK_"a"#, so there should be more A⁻ than HA.

2. Calculate the concentrations

[A⁻] = 3.02[HA]

Also, [A⁻] + [HA] = 1.00 mol/L

3.02[HA] + [HA] = 4.02[HA] = 1.00 mol/L

[HA] = #(1.00"mol/L")/4.02# = 0.2488 mol/L

[A⁻] = 3.02[HA] = 3.02 × 0.2488 mol/L = 0.7512 mol/L

3. Calculate the masses of NaHCO₃ and of Na₂CO₃

Mass of NaHCO₃ = 0.1000 L × #(0.2488"mol NaHCO₃")/(1"L") × (84.01"g NaHCO₃")/(1"mol NaHCO₃")# = 2.09 g NaHCO₃ (3 significant figures)

Mass of Na₂CO₃ = 0.1000 L × #(0.7512"mol Na₂CO₃")/(1"L") × (106.0"g Na₂CO₃")/(1"mol Na₂CO₃")# = 7.96 g Na₂CO₃ (3 significant figures)

You would transfer 2.09 g of NaHCO₃ and 7.96 g of Na₂CO₃ to a 100 mL volumetric flask and make up to the mark with distilled water.

Sign up to view the whole answer

By signing up, you agree to our Terms of Service and Privacy Policy

Sign up with email
Answer 2

To make 100.0 ml of a 1.00 mol/L buffer solution with a pH of 10.80 using only sodium carbonate (Na2CO3), sodium hydrogen carbonate (NaHCO3), and water, you would mix the two components in such a way that the resulting solution has the desired pH. To calculate the amounts needed, you'd use the Henderson-Hasselbalch equation. First, determine the ratio of the concentrations of the conjugate base (Na2CO3) to the weak acid (H2CO3), which is the desired buffer system. Then, use this ratio to find the amounts of each compound needed to prepare the buffer solution.

Sign up to view the whole answer

By signing up, you agree to our Terms of Service and Privacy Policy

Sign up with email
Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

Not the question you need?

Drag image here or click to upload

Or press Ctrl + V to paste
Answer Background
HIX Tutor
Solve ANY homework problem with a smart AI
  • 98% accuracy study help
  • Covers math, physics, chemistry, biology, and more
  • Step-by-step, in-depth guides
  • Readily available 24/7