Chemistry Molarity Quiz

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Questions and Answers

Define molarity and explain how it is calculated.

Molarity is the number of moles of solute present in one liter of solution. It is calculated using the formula $M = \frac{moles}{liters}$.

What is the relationship between moles and grams for a substance?

The relationship is given by $moles = \frac{g}{form.wt}$, meaning moles are calculated by dividing the mass of the substance by its formula weight.

How can you calculate the mmoles of a titrant used in a titration?

The mmoles of a titrant can be calculated using the formula $mmoles = (M)(ml)$ where M is the molarity and ml is the volume in milliliters.

Explain the significance of the reacting ratio in a titration.

The reacting ratio is significant because it indicates the proportions of moles of titrant and titrated substance in the reaction, derived from the balanced equation. Signup and view all the answers

What formula would you use to calculate the grams of solute from the volume and molarity of a solution?

The formula is $g = (liters)(M)(form.wt)$, where liters is the volume in liters, M is the molarity, and form.wt is the formula weight. Signup and view all the answers

How do you calculate the molarity of a solution using the weight of KHP and the volume of NaOH used?

Molarity is calculated using the formula $M = \frac{0.002 \text{ mol}}{0.0367 \text{ L}}$, resulting in 0.0548 M. Signup and view all the answers

Why is normality preferred over molarity in certain chemical reactions?

Normality is preferred because it accounts for reacting ratios that are not 1:1, allowing for more accurate calculations. Signup and view all the answers

Explain the significance of an equivalent in acid-base reactions.

An equivalent signifies the amount of a substance that can react with one Avogadro number of hydrogen ions (H+). Signup and view all the answers

What is the relationship between equivalents and grams in the context of acid-base reactions?

1 equivalent of a substance corresponds to the grams that can react with one mole of H+, such as 36.5 g of HCl being 1 equivalent. Signup and view all the answers

In the example given, what are the moles of KHP calculated from the provided mass?

The moles of KHP are calculated as $\frac{410.4 \text{ mg}}{204.2 \text{ g/mol}} = 0.00200 \text{ mol}$. Signup and view all the answers

Define normality and explain how it relates to equivalent weight in acid-base titrations.

Normality is defined as the number of equivalents of solute per liter of solution, which relates to equivalent weight by the equation: $eq.wt = \frac{form.wt}{No.ofH^+}$. Signup and view all the answers

In the given titration example, how is the normality of the HCl solution calculated from the given data?

The normality of the HCl solution is calculated using the equation: $N_{HCl} = \frac{(32.20)(0.0950)}{25.00}$ resulting in $N_{HCl} = 0.1224$. Signup and view all the answers

Explain the significance of milliequivalents in determining the endpoint of a titration.

At the endpoint of a titration, the milliequivalents of titrant A equals the milliequivalents of titrated substance B, ensuring stoichiometric balance. Signup and view all the answers

What is the relationship between normality and molarity in titration calculations?

Normality and molarity are directly related in titration calculations through the equation: $m_1A N_A = m_2B N_B$. Signup and view all the answers

If 50 mL of a 0.1 N H2SO4 solution is used, how would you determine the equivalent weight for its usage in a titration?

The equivalent weight for H2SO4 in this scenario is determined using the formula: $eq.wt = \frac{form.wt}{2}$, since it can donate two protons. Signup and view all the answers

How are the moles of substance B determined from the moles of substance A in a chemical reaction?

The moles of substance B are determined using the combining ratio (R), based on the stoichiometric coefficients of B and A in the balanced equation. Signup and view all the answers

What is the formula to calculate the weight of substance B in milligrams?

The weight of substance B in milligrams is calculated using the formula mgB = mla * (MA / R) * (form. wt. B). Signup and view all the answers

Explain how to calculate the percentage of substance B in a sample.

The percentage of substance B is calculated by dividing the weight of B in milligrams by the weight of the sample in milligrams and multiplying by 100. Signup and view all the answers

What is the significance of the combining ratio (R) in chemical reactions?

The combining ratio (R) represents the ratio of the stoichiometric coefficients of substances in the balanced chemical equation, essential for mole calculations. Signup and view all the answers

In the example provided, how much acetic acid is present in the vinegar sample?

The weight of acetic acid present is 210.1 mg CH₃COOH. Signup and view all the answers

Describe how to determine the molarity of a solution from a standardization titration.

The molarity of a solution can be determined by titrating a primary standard with known weight and calculating using the formula (mla)(MA)(R)(form wt. B) = mgB. Signup and view all the answers

What factors impact the calculation of the weight of substance B when substituting values?

The calculation of weight of substance B depends on the millimoles of A, its molecular weight, and the combining ratio (R). Signup and view all the answers

How does the reaction ratio (R) influence the conversion of moles between substances A and B?

The reaction ratio (R) serves as a multiplier, adjusting the moles of substance A to determine the proportional moles of substance B produced. Signup and view all the answers

Flashcards

Mole

The amount of substance containing as many elementary entities as there are atoms in 0.012 kilogram of carbon-12. It's essentially a unit of measurement for chemists.

Molarity

The concentration of a solution expressed as the number of moles of solute per liter of solution.

Titration

A chemical reaction where a solution of known concentration (titrant) is added to a solution of unknown concentration (analyte) until the reaction is complete.

Reacting Ratio

The ratio of moles of titrant to moles of analyte in a balanced chemical equation. It tells you how many moles of each substance are involved in the reaction.