High-purity silicon is obtained using a three-step process. the first step involves heating solid silicon dioxide, sio2, with solid carbon to give solid silicon and carbon monoxide gas. in the second step, solid silicon is converted into liquid silicon tetrachloride, sicl4, by treating it with chlorine gas. in the last step, sicl4 is treated with hydrogen gas to give ultrapure solid silicon and hydrogen chloride gas. part a write balanced chemical equations for the first step involved in this three-step process. express your answer as a chemical equation. identify all of the phases in your answer.