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Correct Answer: A
Correct Answer: A
Method / Topic: General Chemistry
The correct option matches the required rule and the given information.
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Correct Answer: A
Method / Topic: General Chemistry
Initially, HCl amount = 50.0 mL × 0.200 mmol/mL = 10.0 mmol. The leftover HCl is measured by NaOH: 20.0 mL × 0.100 mmol/mL = 2.00 mmol. Because HCl and NaOH react 1:1, 2.00 mmol HCl remained. Therefore the tablet consumed 10.0 − 2.00 = 8.00 mmol HCl. This result follows from the balanced chemical relationship and the stated conditions; no unstated biological assumption is needed. On MCAT chemistry problems, first identify the governing principle, write the relevant equation with units, and only then substitute values. Check whether the
prevents dosage, dilution, and preparation errors.
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PASSAGE 1 — ANTACID BACK-TITRATION A laboratory evaluates a 0.500 g antacid tablet whose active ingredient is calcium carbonate, CaCO3. The tablet is treated with 50.0 mL of 0.200 M HCl. Calcium carbonate reacts according to CaCO3(s) + 2H+(aq) → Ca2+(aq) + CO2(g) + H2O(l). After the reaction is complete, the remaining acid requires 20.0 mL of 0.100 M NaOH for neutralization. Assume that other tablet ingredients do not react with either acid or base. QUESTION 1: How many millimoles of HCl were consumed by the tablet?
Explanation
Correct Answer: A
Method / Topic: General Chemistry
The correct option matches the required rule and the given information.
Short Explanation
Detailed Explanation
Correct Answer: A
Method / Topic: General Chemistry
Initially, HCl amount = 50.0 mL × 0.200 mmol/mL = 10.0 mmol. The leftover HCl is measured by NaOH: 20.0 mL × 0.100 mmol/mL = 2.00 mmol. Because HCl and NaOH react 1:1, 2.00 mmol HCl remained. Therefore the tablet consumed 10.0 − 2.00 = 8.00 mmol HCl. This result follows from the balanced chemical relationship and the stated conditions; no unstated biological assumption is needed. On MCAT chemistry problems, first identify the governing principle, write the relevant equation with units, and only then substitute values. Check whether the
prevents dosage, dilution, and preparation errors.
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