AS chemistry please help!Watch this thread
Our bodies are approximately 60% water. Using the assumption that our bodies are completely water, and the average person weights around 75kg, how many molecules are there in the human body?
1. moles = mass/Mr.
2. moles = number of molecules/Avogadro's constant.
Not allowed to give straight answers, sorry.
number of particles = mass of substance / Molar mass (this is equal to the relative atomic mass)
- How do I find the number of moles of something? (this will come in handy for the next equation.)
- What do I multiply the number of moles of a substance by to find the number of molecules? (rhymes with 'avocado')
Approximately, yes. I'm guessing you used 18 for the Mr value of water rather than 18.02? My answer is off by only a few decimal places so your answer would still be accepted unless the examiners had supplied the Ar of each element in the question and you failed to use it correctly.
The question is calculate atom economy to make iron from iron oxide?