C.4.4 Apply the mole concept to determine the mass, moles, number of particles, or volume of a gas at STP, in any given sample, for an element or compound.
Learning Goal:
I can use the mole concept to determine the mass, moles, and number of particles in any sample.
Need - paper, pencil, and a scientific calculator
Recommended Free Calculators - natural scientific calculator or Demos
C.4.4 Apply the mole concept to determine the mass, moles, number of particles, or volume of a gas at STP, in any given sample, for an element or compound.
Learning Goal:
I can use the mole concept to determine the mass, moles, and number of particles in any sample.
Need - paper, pencil, and a scientific calculator
Recommended Free Calculators - natural scientific calculator or Demos
SigFig Rules:
All non-zero digits are significant (211.8 has four sigfigs).
Zeros between non-zero digits are significant (20,007 has five sigfigs).
Leading zeros in a number are not significant (0.0085 has two sigfigs).
Trailing zeros in a decimal number are not significant unless there is a decimal in the number (0.0050 has two sigfigs; 4100.0 has five sigfigs).
Trailing zeros in a whole number without a decimal are not significant (1000 has one sigfig).
Rounding after solving a problem:
If the original number was 2.140 x 107
Four sigfigs (2.140); therefore, the answer must also have four sigfigs.
If the product was 1.150672 x 105, then it would need to be rounded to 1.151 x 105.
Question 1
1.
How many atoms are there in a 591 g sample of gold (Au)?
_______ atoms Au
Round to the nearest hundredth.
Question 2
2.
How many atoms are in 4.000 moles of carbon (C)?
_______ mol C
Round to the nearest thousandth.
Question 3
3.
How many moles are in 68 g of carbon (C)?
_______ mol C
Round to the nearest tenth.
Question 4
4.
How many moles are in 105 g of sulfur (S)?
_______ mol S
Round to the nearest hundredth.
Question 5
5.
How many atoms are there in 0.802 g Hg?
_______ atoms Hg
Round to the nearest hundredth.
Question 6
6.
What is the molar mass of C2H8?
_______ g C2H8
Round to the nearest thousandth.
Question 7
7.
How many molecules of C2H8 are there in 4.01x105 g C2H8?
Hint - you calculated the molar mass in question 8.
_______ molecules C2H8
Round to the nearest hundredth.
Question 8
8.
What is the mass (in grams) of 9.52 x 106 molecules of C2H8?
Hint - you calculated the molar mass in number 8.
_______ g C2H8
Round to the nearest hundredth.
Stop, here.
Need - scientific calculator, paper, pencil.
Recommended Calculator for Cellphone - natural scientific calculator or Desmos for computer/Chromebook
This section is independent work - 5 questions.
Identify what you have (mass, moles, or particles).
Identify what the question wants you to convert it to.
Look at the provided conversion chart and identify what conversion factor you need (molar mass or Avogadro's number).
Look at the arrows on the chart to identify if you are multiplying or dividing by that conversion factor.
SigFigs - identify how many significant figures the number in the question has (zeros by themselves to the left of the decimal are usually not significant; zeros to the right of the decimal usually are) and round your answer to ensure that it has the same number of significant figures.
I'm here to help; let me know if you are confused with any of this.
SigFig Rules:
All non-zero digits are significant (211.8 has four sigfigs).
Zeros between non-zero digits are significant (20,007 has five sigfigs).
Leading zeros in a number are not significant (0.0085 has two sigfigs).
Trailing zeros in a decimal number are significant unless they are before a decimal (0.0050 has two sigfigs; 4100.0 has four sigfigs).
Trailing zeros in a whole number are not significant (1000 has 1 sigfig).
Question 9
9.
What is the mass (in grams) of 4.25 x 103 moles of N2?
Hint - convert your answer into scientific notation; you will move the decimal left, 5 places, which will determine the exponent over the 10.
_______ g N2
Answer in scientific notation and round to the nearest hundredth.
Question 10
10.
How many molecules of N2 are there in 4.25 x 103 moles of N2?
_______ molecules N2
Round to the nearest hundredth.
Question 11
11.
How many grams are in 2.20 x 10-3 moles of tin (Sn)?
_______ g Sn
Round to the nearest thousandth.
Question 12
12.
How many moles are in 72.0 g of argon (Ar)?
_______ mol Ar
Round to the nearest hundredth.
Question 13
13.
How many moles are in 10.0 grams of chromium (Cr)?
_______ mol Cr
Round to the nearest thousandth.
Question 14
14.
How many molecules are in 1.24 mol dichloride gas (Cl2)?
_______ molecules Cl2
Round to the nearest hundredth.
Question 15
15.
Convert the following using a two-step conversion: first from mass to moles and then from moles to the desired quantity of molecules.
How many molecules in 60.0 g of N2O?
_______ molecules N2O
Round to the nearest hundredth.
Question 16
16.
How many molecules are in 69.236 g of PbO?
_______ molecules PbO
Round to the nearest thousandth.
Need - scientific calculator, paper, pencil.
Recommended Calculator for Cellphone - natural scientific calculator or Desmos for computer/Chromebook
This section is independent work - 5 questions.
Identify what you have (mass, moles, or particles).
Identify what the question wants you to convert it to.
Look at the provided conversion chart and identify what conversion factor you need (molar mass or Avogadro's number).
Look at the arrows on the chart to identify if you are multiplying or dividing by that conversion factor.
SigFigs - identify how many significant figures the number in the question has (zeros by themselves to the left of the decimal are usually not significant; zeros to the right of the decimal usually are) and round your answer to ensure that it has the same number of significant figures.
I'm here to help; let me know if you are confused with any of this.
SigFig Rules:
All non-zero digits are significant (211.8 has four sigfigs).
Zeros between non-zero digits are significant (20,007 has five sigfigs).
Leading zeros in a number are not significant (0.0085 has two sigfigs).
Trailing zeros in a decimal number are significant unless they are before a decimal (0.0050 has two sigfigs; 4100.0 has four sigfigs).
Trailing zeros in a whole number are not significant (1000 has 1 sigfig).
Question 17
17.
Question 18
18.
a.) How many moles of CO2 are in 254 g of it?
_______ moles CO2
Round to the nearest hundredth.
b.) How many molecules are in 254 g CO2?
_______
Round to the nearest hundredth.
Question 19
19.
a.) What is the molar mass of AgNO3?
_______ g/mol AgNO3
Round to the nearest hundredth.
b.) How many molecules are in 50.245 g AgNO3?
_______ molecules AgNO3
Round to the nearest thousandth.
a.) What is the molar mass of CH3CH2OH?
_______ g/mol
Round to the nearest thousandth.
b.) What is the mass 0.5623 mol of CH3CH2OH?
_______ g CH3CH2OH
Round to the nearest hundredth.
c.) How many moles are in 100.0 g of CH3CH2OH?
_______ mol CH3CH2OH
Round to the nearest thousandth.
d.) How many molecules of CH3CH2OH are in 50.2 g of it?