1.1 Moles and Molar Mass

ID: kojis-varig
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Subject: Chemistry
Grade: 10-12

This Grade 10-12, AP assignment contains 12 questions where students focus on Moles and Molar Mass. These exercises provide practice for Atomic Structures and Properties. For calculations in this assignment, molar masses for elements are taken from ptable.com. Avogadro's number is used with 3 significant figures in calculations. All answers are rounded to the appropriate number of significant figures.

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12 questions

1.1 Moles and Molar Mass

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Formula to Molar Mass

1) Determine the molar mass of (NH4)2SO4(NH_{4})_{2}SO_{4} in gmol\frac{g}{mol}.

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2) 1 gram 1\text{ gram }samples of each of the following substances are measured. Which sample will contain the largest number of molecules?

a)

H3O+1H_{3}O^{+1}

b)

C2O42C_{2}O^{2-}_{4}

c)

NH4+1NH^{+1}_{4}

d)

NO31NO^{-1}_{3}

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3) Determine the molar mass (gmol)\left(\frac{g}{mol}\right) of the ionic compound consisting of Al3+ and SO42Al^{3+}\text{ and }SO_4^{2-}.

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Avogadro's Number and Mass

For the following, assume 1 mol=6.02×10231\text{ mol}=6.02\times10^{23} representative particles.

4) How many formula units are present in a 2.00 gram 2.00\text{ gram }sample of NaCH3COONaCH_3COO?

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5) What is the mass (g)(g)of 2.21×10122.21\times10^{12}molecules of glucose, C6H12O6C_6H_{12}O_6?

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6) How many molecules are present in a 0.002500.00250 gram sample of HCOOHHCOOH?

Comparing Quantities

7) The chemical formula of Ibuprofen is C13H18O2C_{13}H_{18}O_2. Evaluate the following statement.


"154.7 g154.7\text{ g} is a larger sample than 3.612×10233.612\times10^{23}molecules"

True or false? Write below.
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8) Three samples of Carbon Dioxide, CO2(g)CO_{2(g)}, are measured. Arrange the samples from the smallest quantity to the largest quantity by listing the sample number and using a comparison symbol.

For example:  1<2<3 \ 1<2<3\ , if Sample 33 is the largest and Sample 11 is the smallest.


SampleQuantity16.02×1023 moles26.02×1023 grams36.02×1023 molecules\begin{array}{|c|c|} \hline \\[-1em] \text{Sample}&\text{Quantity}\\[-1em]\\ \hline \\[-1em]1&6.02\times 10^{23}\text{ moles}\\[-1em]\\ \hline \\[-1em]2&6.02\times10^{23}\text{ grams}\\[-1em]\\ \hline \\[-1em]3&6.02\times10^{23}\text{ molecules}\\[-1em]\\ \hline \end{array}

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9) Four samples of water are measured. Arrange the samples from the smallest quantity to the largest quantity by listing the sample number and using a comparison symbol.

For example: A < B < C < DA\ <\ B\ <\ C\ <\ D


H2O(l) SampleQuantityA0.3500 gB0.1000 molC1.084×1024 moleculesD18.00 g\begin{array}{|c|c|} \hline \\[-1em] H_2O_{(l)}\text{ Sample}&\text{Quantity}\\[-1em]\\ \hline \\[-1em]A&0.3500\text{ g}\\[-1em]\\ \hline \\[-1em]B&0.1000\text{ mol}\\[-1em]\\ \hline \\[-1em]C&1.084\times10^{24}\text{ molecules}\\[-1em]\\ \hline \\[-1em]D&18.00\text{ g}\\[-1em]\\ \hline \end{array} 

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Molar Masses

10) A 0.2500 mol0.2500\text{ mol} sample of a certain element is determined to have a mass of 7.7426 g7.7426\text{ g}. What is the molar mass (gmol)\left(\frac{g}{mol}\right) of the substance?

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11) Write the chemical symbol of the element from question 10)10).

12) What is the molar mass (gmol1)\left(\text{g}\cdot\text{mo}l^{-1}\right) of a sample if 2.54×10222.54\times10^{22} molecules has a mass of 2.00×102 kg2.00\times10^{-2}\text{ kg}? (1 kg=1000 g)\left(1\text{ kg}=1000\text{ g}\right)