How many molecules are in 237 g (about a cup) of water?

4 Answers

• Molar mass H2O = 18g/mol

  237g = 237/18 = 13.17 mol

  1 mol = 6.022*10^23 molecules

  13.17 mol = 6.022*10^23*13.17 = 7.93*10^24 – Choice D) is correct.

• Quick answer: 6.873E24molecules

  At no extreme pressure, vacuum, temperature (+,-) the diameter of each water molecule is about 0.29nanometer. Each meter is 10^9nonos, or each cm=10^9/100=10^7nanos. A cup of 12Oz, (237mL) water is 1cm^3X237=237mL, therefore, water molecule is 0.29X100=29nanocm, volume of 1cm^3=1X1X1=1mL, which is 10^7X10^7X10^7=10^21=1.0E21nanos in 1cc or 1mL, thus there are 1.0E21X29=2.9E22molecules per 1cc or 1mL, therefore, 237X29X10^21=6873X10^21, or 6.873E24molecules (water-molecules).

  Interesting:

  The distance from the Earth to the Moon is about 384X10^3km (closest), or 384X10^3X10^3=3.84E8meters, if we line up the molecules of a cup of water (237mL), which are 6.873E24molecules, will make a line 6.873E24X0.29/10^9=1.99317E15meter-long. Now, if we divide the length of the lined-up cup’s water molecules by the Earth and the Moon distance numbers, will have a number, which is (1.99317E15/3.84E8=5.19E6#5.2E6) 2+1/2-round-tripped-trip/long to the Moon, however, we’ll need more water to come back to our planet Earth.

• 1 mole of any substance =6.023*10^23 particles(atom,molecule,electron gram formula—).

  1mole of water=18gm where X is the unknown number of mole of water in 237gm

  X=273gm

  X=273g*1mole/18gm/mole

  x=15.2mole.

• determine no. of moles of water: 237 g/18 g/mole H2O= 13.17 moles H2O

  13.17 moles H2O x 6.02E23 molecules/mole= 7.93E24 molecules of water