# Tutor profile: Katie S.

## Questions

### Subject: Chemistry

How many molecules are in 15 grams of water?

To answer this question, first you would need to convert the grams of water into moles of water. To do this, you need to divide the 15 grams of water by the molar mass of water, which is 18.02 g/mol. Therefore: 15 g / 18.02 g/mol = 0.832 moles. The grams will cancel out leaving the moles as the unit for your answer. Now, to get moles into molecules you will need to use Avogadro's number which is 6.022 x 10^23 molecules/moles. Therefore: 0.832 moles * 6.022 x 10^23 molecules/moles = 5.01 x 10^23 molecules. To conclude, there are 5.01 x 10^23 molecules in 15 grams of water.

### Subject: Basic Chemistry

What is the atomic symbol and atomic weight of sodium?

The atomic symbol of sodium is Na. The atomic weight of sodium is 22.99 g/mol.

### Subject: Biology

What is one difference between a prokaryotic and eukaryotic cell?

There are several characteristics that differentiate between a eukaryotic and prokaryotic cell. For example, only eukaryotes have membrane-bound organelles (such as mitochondria and chloroplast), a nucleus, linear DNA, ribosomes, and can reproduce sexually. Another difference is that only prokaryotes have a cell wall.

## Contact tutor

needs and Katie will reply soon.