Question

Sulfur trioxide reacts with water to form sulfuric acid according to the following reaction:

SO3 + H2O → H2SO4

Sulfuric acid (H2SO4) has the atomic mass of 98 amu, hydrogen (H) has an atomic mass of 1 amu, and oxygen (O) has the atomic mass of 16 amu. Use this information to figure out the atomic mass of sulfur (S) and then use that number to calculate the atomic mass of sulfur trioxide (SO3).

(1 point)
Responses

116 amu
116 amu

80 amu
80 amu

48 amu
48 amu

32 amu

Answer 1

To find the atomic mass of sulfur (S), we can use the molar mass of sulfuric acid (H2SO4) and the atomic masses of the other elements in the formula.

The molar mass of H2SO4 can be calculated as follows:
- Hydrogen (H): 2 atoms × 1 amu = 2 amu
- Sulfur (S): 1 atom × S amu = S amu
- Oxygen (O): 4 atoms × 16 amu = 64 amu

The total mass of H2SO4 is:
\[ 2 \text{ amu (H)} + S \text{ amu (S)} + 64 \text{ amu (O)} = 98 \text{ amu} \]

Now, let's put the values into the equation:
\[ 2 + S + 64 = 98 \]

Simplifying the equation:
\[ S + 66 = 98 \]
\[ S = 98 - 66 \]
\[ S = 32 \text{ amu} \]

Now that we have the atomic mass of sulfur (S = 32 amu), we can calculate the atomic mass of sulfur trioxide (SO3):

SO3 consists of:
- 1 atom of sulfur (S): 32 amu
- 3 atoms of oxygen (O): 3 × 16 amu = 48 amu

Adding these together for SO3:
\[ 32 \text{ amu (S)} + 48 \text{ amu (O)} = 80 \text{ amu} \]

Therefore, the atomic mass of sulfur trioxide (SO3) is **80 amu**.

So, the correct response is:
80 amu