Determine the number of moles (of molecules or formula units) in each sample. a. 25.5 g NO 2 b. 1.25 kg CO 2 c. 38.2 g KNO 3 d. 155.2 kg Na 2 SO 4

Hey everyone. Our questionnaire asks us how many moles are in 175 kg of barium sulfide. We're first going to need to calculate our molar mass in order to answer this question So we can see that we have one of barium and we're going to multiply that by its atomic mass of 137.327 g per mole. And that's going to get us to 137.3 - seven. Next we have one of sulfur And we're going to multiply that by its atomic mass of 32.066, Which again will get us at 32.066 Adding these two up, we end up with a molar mass of 169. grams per mole. Now moving on to our question, we're going to start off with our 175 kg of barium sulfide And we want to convert this into Graham's first and we know that per one kg we have 10 to the 3rd g. And we're going to input our molar mass that we calculated and we know that we have 100 and 69.393 g per one mole of barium sulfide. And when we calculate this out and cancel out our units, we end up with a value of 1.03 times 10 to the third mole of barium sulfide, which is our final answer. So I hope this made sense. And let us know if you have any questions

Ch.3 - Molecules, Compounds & Chemical Equations

Tro - Chemistry: A Molecular Approach 4th Edition

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Ch.3 - Molecules, Compounds & Chemical Equations

Problem 63

Chapter 3, Problem 63

Determine the number of moles (of molecules or formula units) in each sample. a. 25.5 g NO₂ b. 1.25 kg CO₂ c. 38.2 g KNO₃ d. 155.2 kg Na₂SO₄

Verified step by step guidance

insert step 1: Identify the molar mass of each compound using the periodic table. For example, calculate the molar mass of NO_2 by adding the atomic masses of nitrogen (N) and oxygen (O).

insert step 2: Convert the mass of each sample to grams if necessary. For instance, convert 1.25 kg of CO_2 to grams by multiplying by 1000.

insert step 3: Use the formula: number of moles = mass of sample (g) / molar mass (g/mol) to calculate the moles for each compound.

insert step 4: Apply the formula to each sample: a. 25.5 g NO_2, b. 1.25 kg CO_2, c. 38.2 g KNO_3, d. 155.2 kg Na_2SO_4.

insert step 5: Ensure all calculations are consistent with significant figures based on the given data.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is calculated by summing the atomic masses of all the atoms in a molecule or formula unit. For example, the molar mass of NO2 is approximately 46.01 g/mol, which is essential for converting grams to moles.

Conversion between Mass and Moles

To determine the number of moles from a given mass, the formula used is: moles = mass (g) / molar mass (g/mol). This relationship allows chemists to convert between the mass of a substance and the amount in moles, facilitating stoichiometric calculations in chemical reactions.

Unit Conversion

Unit conversion is the process of converting a quantity expressed in one unit to another unit. In this question, it is necessary to convert kilograms to grams for CO2 and Na2SO4, as the molar mass is typically given in grams per mole. Understanding how to perform these conversions is crucial for accurate calculations.