Question

the balloons at a childs birthday party are filled with helium (he). how many moles of helium atoms are in a balloon that contains 2.53 grams of helium? refer to a periodic table. write your answer to the correct number of significant figures. round if necessary. moles

Explanation:

Step1: Identify molar - mass of helium

From the periodic table, the molar - mass of helium (He) is approximately 4.00 g/mol.

Step2: Use the mole formula

The formula to calculate the number of moles ($n$) is $n=\frac{m}{M}$, where $m$ is the mass and $M$ is the molar - mass. Given $m = 2.53$ g and $M=4.00$ g/mol, we substitute these values into the formula: $n=\frac{2.53}{4.00}$.

Step3: Calculate the number of moles

$n = 0.6325$ moles. Rounding to three significant figures (since 2.53 has three significant figures), $n = 0.633$ moles.

Answer:

0.633