Titanium dioxide and zinc oxide are two of the 16 active ingredients approved by the FDA for use in sunscreens. Which compound contains a higher percentage of oxygen by mass

The compound with the higher percentage of oxygen by mass is titanium dioxide.

Titanium dioxide, TiO2, has a molar mass of 79.866 g/mol and O2 has a molar mass of 32.

Percentage by weight of oxygen in TiO2 = 32/79.866 x 100

                                                          = 40.07%

Zinc oxide, ZnO, has a molar mass of 81.38 g/mol

percentage by weight of oxygen in ZnO = 16/81.38 x 100

                                                               = 19.66%

Thus, titanium dioxide has a higher percentage by weight of oxygen than zinc oxide.

More on percentage by mass of substances can be found here: link

has higher percentage of oxygen by mass.

Explanation:

To calculate the mass percent of element in a given compound, we use the formula:

1. Mass of oxygen in =

2. Mass of oxygen in =

Thus has higher percentage of oxygen by mass.

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).