Question

question 49 (0.0862 points)
how many milliliters are in 1.75 l?
\\( 1.75 \times 10^3 \\)
\\( 1.75 \times 10^2 \\)
\\( 1.75 \times 10^{-3} \\)
none of these

question 50 (0.0862 points)
how many grams of water are made from the reaction of 4.50 grams of hydrogen gas?
give just the number with the correct significant figures.
\\( 2h_2 + o_2 \
ightarrow 2h_2o \\)

Explanation:

Question 49

Step1: Recall unit conversion

We know that \( 1\space L = 1000\space mL = 1\times10^{3}\space mL \).

Step2: Convert 1.75 L to mL

To convert liters to milliliters, we multiply the number of liters by \( 10^{3} \). So, \( 1.75\space L\times10^{3}\space \frac{mL}{L}=1.75\times 10^{3}\space mL \).

Step1: Find moles of \( H_2 \)

The molar mass of \( H_2 \) is \( 2\space g/mol \). Moles of \( H_2=\frac{mass}{molar\space mass}=\frac{4.50\space g}{2\space g/mol} = 2.25\space mol \).

Step2: Use stoichiometry

From the reaction \( 2H_2+O_2
ightarrow 2H_2O \), the mole ratio of \( H_2 \) to \( H_2O \) is \( 2:2 = 1:1 \). So moles of \( H_2O = 2.25\space mol \).

Step3: Find mass of \( H_2O \)

Molar mass of \( H_2O \) is \( 18\space g/mol \). Mass of \( H_2O=moles\times molar\space mass = 2.25\space mol\times18\space g/mol = 40.5\space g \).

Answer:

A. \( 1.75\times 10^{3} \)

Question 50