First calculate the initial moles of HCl.
HCl moles i = (1.45 moles / L) * 0.5 L = 0.725 moles HCl
Then calculate how much HCl is consumed by stoichiometry:
HCl moles consumed = (12.7 g Zn / 65.38 g / mol) * (2
moles HCl / 1 mole Zn) = 0.388 moles
So HCl moles left is:
HCl moles f = 0.725 – 0.388 = 0.3365 moles
For every 1 mole HCl there is 1 mole H, therefore:
H moles final = 0.3365 moles
So final concentration of H ions is:
<span>Concentration H = 0.3365 moles / 0.5 L = 0.673 M</span>
hold the syringe downward,shake vigorously for sometime,and expel the bubbles through the needle using the syringe plunger. hold the syringe upright, provide a firm tap or flick to the barrel
Answer:
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Answer:
HNO₂ ⇄ H⁺ + NO₂⁻
Ka = 4.0 × 10⁻⁴
Explanation:
Step 1: Given data
- Concentration of nitrous acid (Ca): 0.010 M
Step 2: Write the acid dissociation reaction
Nitrous acid is a weak acid that dissociates according to the following expression.
HNO₂ ⇄ H⁺ + NO₂⁻
Step 3: Calculate the concentration of H⁺
We will use the definition of pH.
pH = -log [H⁺]
[H⁺] = antilog - pH = antilog -2.70 = 2.00 × 10⁻³ M
Step 4: Calculate the acid dissociation constant (Ka)
For a weak acid, we can calculate Ka using the following expression.
Ka = [H⁺]²/Ca
Ka = (2.00 × 10⁻³)²/0.010
Ka = 4.0 × 10⁻⁴
