A new sunscreen has been formulated using titanium dioxide nanoparticles to provide UV protection.
Explain one possible risk of using nanoparticles in cosmetic products like sunscreens.
A cube-shaped titanium dioxide nanoparticle has sides of length 25 nm25\text{ nm}25 nm.
Calculate the surface area to volume ratio for this nanoparticle.
Use the equation: ratio=surface area÷volume\text{ratio} = \text{surface area} \div \text{volume}ratio=surface area÷volume
Scientists compare the size of nanoparticles to the sizes of other small objects.
Look at the table:
| Object | Diameter (nm) |
|---|---|
| Hydrogen atom | 0.12 |
| Water molecule | 0.28 |
| Buckyball (C60C_{60}C60) | 1.1 |
| Titanium dioxide nanoparticle | 25 |
| Spider silk fiber | 4700 |
| Human hair | 78000 |
Explain why a buckyball is a nanoparticle but a water molecule is not a nanoparticle.
Calculate how many titanium dioxide nanoparticles would fit across the width of a spider silk fiber.
Give your answer to 2 significant figures.
Properties of materials Questions
Practise OCR GCSE Chemistry Properties of materials with exam-style questions for Foundation and Higher tier. 60 questions, matched to the OCR GCSE Chemistry (J248) specification and written in Paper 1 and Paper 2 (Foundation Tier) or Paper 3 and Paper 4 (Higher Tier) style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.