Question

key formulas & constants

• 1 mole = 6.022 × 10²³ particles (avogadros number)
• molar mass (m) = mass of 1 mole of a substance (g/mol)

symbols explained
symbol meaning
n amount of substance (in moles)
m mass (in grams)
m molar mass (in g/mol)
n number of particles (atoms, molecules,
formula units, etc.)
nₐ avogadros constant = 6.022 × 10²³
particles/mol
grams ↔ moles
n = m / m (moles = mass ÷ molar mass)
m = n × m (mass = moles × molar mass)
moles ↔ particles
n = n / nₐ (moles = particles ÷ avogadros number)
n = n × nₐ (particles = moles × avogadros number)
part 1: grams ↔ moles

Explanation:

Step1: Calculate moles of NaCl

Use the formula \( n=\frac{m}{M} \). Here, \( m = 11.7\ g \) (mass of NaCl) and \( M = 58.44\ g/mol \) (molar mass of NaCl).
\( n=\frac{11.7}{58.44}\)

Step2: Perform the division

\( n=\frac{11.7}{58.44}= 0.200\ mol\) (rounded to three - significant figures)

Step3: Calculate mass of \(C_{6}H_{12}O_{6}\)

Use the formula \( m=n\times M \). Here, \( n = 2.50\ mol \) (moles of glucose) and \( M = 180.16\ g/mol \) (molar mass of glucose).
\( m=2.50\times180.16\)

Step4: Perform the multiplication

\( m = 2.50\times180.16=450.4\ g\)

Step5: Calculate mass of \(O_{2}\)

Use the formula \( m=n\times M \). Here, \( n = 0.0250\ mol \) (moles of \(O_{2}\)) and \( M = 32.00\ g/mol \) (molar mass of \(O_{2}\)).
\( m=0.0250\times32.00\)

Step6: Perform the multiplication

\( m=0.0250\times32.00 = 0.800\ g\)

Answer:

Substance	Molar Mass (g/mol)	Problem	Show Work (2 pts)	Ans (1 pt)
\(CO_{2}\)	\(44.01\)	What is the mass of \(0.750\ mol\) of carbon dioxide?	\(0.750\times44.01\)	\(33.0\)
\(NaCl\)	\(58.44\)	Convert \(11.7\ g\) of table salt to moles.	\(11.7\div58.44\)	\(0.200\)
\(C_{6}H_{12}O_{6}\)	\(180.16\)	How many grams are in \(2.50\ mol\) of glucose?	\(2.50\times180.16\)	\(450.4\)
\(O_{2}\)	\(32.00\)	Find the mass of \(0.0250\ mol\) of oxygen gas.	\(0.0250\times32.00\)	\(0.800\)