If the equilibrium concentration of CH_4 is 0.00045 mol/L, which of the following correctly expresses this value in scientific notation?

• A. 4.5 × 10^{-3} mol/L
• B. 45 × 10^{-4} mol/L
• C. 4.5 × 10^{-4} mol/L
• D. 4.5 × 10^{-5} mol/L

Answer: (C)

Verified step by step guidance

1. Identify the given concentration value: 0.00045 mol/L.
2. Recall that scientific notation expresses numbers as a product of a number between 1 and 10 and a power of 10, i.e., \(a \times 10^{n}\) where \$1 \leq a < 10\( and \)n$ is an integer.
3. Convert 0.00045 to scientific notation by moving the decimal point to the right of the first non-zero digit. Count how many places the decimal moves to determine the exponent.
4. Express 0.00045 as \$4.5 \times 10^{-4}$ mol/L because moving the decimal point 4 places to the right converts 0.00045 to 4.5.
5. Compare this result with the given options to identify the correct scientific notation expression.