How many moles of water are there in 1.00 L at STP? How many molecules?

검증된 단계별 안내

Determine the density of water at standard temperature and pressure (STP). The density of water is approximately 1.00 g/mL, which means 1.00 L of water has a mass of 1000 g.

Calculate the molar mass of water (H₂O). The molar mass is the sum of the atomic masses of its elements: hydrogen (H) has an atomic mass of approximately 1.01 g/mol, and oxygen (O) has an atomic mass of approximately 16.00 g/mol. Therefore, the molar mass of water is \( 2(1.01) + 16.00 = 18.02 \) g/mol.

Use the formula \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \) to calculate the number of moles of water. Substitute the mass of water (1000 g) and the molar mass of water (18.02 g/mol) into the formula.

To find the number of molecules, use Avogadro's number, which is \( 6.022 \times 10^{23} \) molecules/mol. Multiply the number of moles of water by Avogadro's number to determine the total number of water molecules.

Express the final answers in terms of moles and molecules, ensuring the units are consistent and properly labeled.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Molarity and Moles

Molarity is a measure of concentration defined as the number of moles of solute per liter of solution. In this context, to find the number of moles of water in 1.00 L, we use the molar mass of water (approximately 18.02 g/mol) and the density of water (about 1 g/mL) to determine that 1 L of water contains roughly 55.5 moles.

Avogadro's Number

Avogadro's number, approximately 6.022 x 10^23, is the number of particles (atoms, molecules, etc.) in one mole of a substance. This constant allows us to convert between moles and the number of molecules. For example, to find the number of molecules in the calculated moles of water, we multiply the number of moles by Avogadro's number.

Standard Temperature and Pressure (STP)

Standard Temperature and Pressure (STP) is a reference point used in chemistry, defined as 0 degrees Celsius (273.15 K) and 1 atmosphere of pressure. At STP, gases behave ideally, and it provides a consistent basis for calculations involving gases and solutions. While the question focuses on water, understanding STP is crucial for contextualizing the conditions under which the calculations are made.