The ruby red color, the golden-green emerald color provides a compound consisting of two elements

| September 9, 2021 | education

The ruby red color, the golden-green emerald color provides a compound consisting of two elements – chromium and oxygen. A sample of a substance weighing 30.4 g contains 9.6 g of oxygen. Find the chromium content. Give the answer in the form of an ordinary fraction.

Given:
m (CrxOy) = 30.4 g
m (O) = 9.6 g

Find:
ω (Cr) -?
CrxOy -?

1) Calculate the mass Cr:
m (Cr) = m (CrxOy) – m (O) = 30.4 – 9.6 = 20.8 g;
2) Calculate the mass fraction of Cr:
ω (Cr) = m (Cr) / m (CrxOy) = 20.8 / 30.4 = 13/19;
3) Calculate the amount of substance Cr:
n (Cr) = m (Cr) / M (Cr) = 20.8 / 52 = 0.4 mol;
4) Calculate the amount of substance O:
n (O) = m (O) / M (O) = 9.6 / 16 = 0.6 mol;
5) Derive the formula for an unknown substance:
x: y = n (Cr): n (O) = 0.4: 0.6 = 1: 1.5 = 2: 3;
Cr2O3.

Answer: Mass fraction of Cr is 13/19; unknown substance – Cr2O3.



One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.