If 175 undecayed nuclei remained from a sample of 2800 nuclei, how many half-lives has passed? *
2 answers:
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Answer:
B.) 2 HCl(aq) + CaCO₃(s) → CaCl₂(aq) + H₂O(l) + CO₂(g)
C.) 7.4 × 10² mL
D.) 2 HCl(aq) + Mg(OH)₂(aq) → MgCl₂(aq) + H₂O(l)
E.) 1.3 × 10³ mL
Explanation:
<em>The daily output of stomach acid (gastric juice) is 1000 to 2000 mL. Prior to a meal, stomach acid (HCl) typically has a pH of 1.49.</em>
We can calculate the concentration of H⁺ using the definition of pH.
pH = -log [H⁺]
[H⁺] = antilog -pH = antilog (-1.49) = 0.0324 M
Since HCl is a strong monoprotic acid, we can consider this to be the concentration of HCl as well.
<em>B.) One chewable tablet of the antacid Maalox contains 600 mg of CaCO₃. Enter the neutralization equation. Express your answer as a molecular equation including phases.</em>
The neutralization equation is:
2 HCl(aq) + CaCO₃(s) → CaCl₂(aq) + H₂O(l) + CO₂(g)
<em>C.) Given that one chewable tablet of the antacid Maalox contains 600 mg of CaCO₃, calculate the milliliters of stomach acid neutralized by two tablets of Maalox. Express the volume in milliliters to two significant figures.</em>
We can establish the following relations:
- Each tablet has 600 mg (0.600 g) of CaCO₃.
- The molar mass of CaCO₃ is 100.09 g/mol.
- The molar ratio of HCl to CaCO₃ is 2:1.
- The concentration of HCl is 0.0324 mol/L.
The mililiters of HCl that neutralize 2 tablets of Maalox are:
<em>D.) The antacid milk of magnesia contains 400 mg of Mg(OH)₂ per teaspoon. Enter the neutralization equation. Express your answer as a molecular equation including phases.</em>
The neutralization equation is:
2 HCl(aq) + Mg(OH)₂(aq) → MgCl₂(aq) + H₂O(l)
<em>E.) Given that the antacid milk of magnesia contains 400 mg of Mg(OH)₂ per teaspoon, calculate the number of milliliters of stomach acid that are neutralized by 1 tablespoon of milk of magnesia. (1 tablespoon = 3 teaspoons.)Express the volume in milliliters to two significant figures.</em>
We can establish the following relations:
- 1 tablespoon = 3 teaspoons
- 1 teaspoon contains 400 mg (0.400 g) of Mg(OH)₂
- The molar mass of Mg(OH)₂ is 58.32 g/mol.
- The molar ratio of HCl to Mg(OH)₂ is 2:1.
- The concentration of HCl is 0.0324 mol/L.
The mililiters of HCl that neutralize 1 tablespoon of milf of magnesia are: