Question

how many molecules are in 2.0 moles of co₂?
? × 10^? molecules of co₂
remember: 1 mole = 6.02 × 10^23 molecules
enter the coefficient in the green box and the exponent in the yellow box.

Explanation:

Step1: Use Avogadro's number

We know that \(1\) mole of any substance contains \(6.02\times 10^{23}\) molecules (Avogadro's number \(N_A = 6.02\times 10^{23}\text{ molecules/mol}\)).
For \(n = 2.0\) moles of \(CO_2\), we use the formula \(N=n\times N_A\).
Substitute \(n = 2.0\) mol and \(N_A=6.02\times 10^{23}\text{ molecules/mol}\) into the formula: \(N=(2.0)\times(6.02\times 10^{23})\).

Step2: Calculate the result

Using the rule of multiplication of numbers in scientific - notation \(a\times10^{m}\times b\times 10^{n}=(a\times b)\times10^{m + n}\), here \(a = 2.0\), \(b=6.02\), \(m = 0\), \(n = 23\).
\(N=(2.0\times6.02)\times10^{23}\).
\(2.0\times6.02 = 12.04\).
We can rewrite \(12.04\times 10^{23}\) in proper scientific - notation as \(1.204\times 10^{24}\) (since \(12.04=1.204\times10^{1}\) and \(10^{1}\times10^{23}=10^{24}\)).

Answer:

Coefficient: \(1.2\) (rounded from \(1.204\) considering significant figures, since \(2.0\) has two significant figures), Exponent: \(24\)