The Integrated Circuits in Your Cell Phone and Computer Are

question 13

Multiple Choice

The integrated circuits in your cell phone and computer are made from the semiconductor silicon. The silicon is obtained from a really inexpensive starting material, sand, which is primarily SiO₂. One step in the purification of silicon is to separate it from solid impurities by forming the gas silicon tetrachloride. Given the following reactions, what is the overall enthalpy change in converting 1.00 mol of silicon dioxide into pure silicon? Reaction
H° (kJ)
SiO₂(s) + 2C(s)  Si(impure s) + 2CO(g)
+690
Si(impure s) + 2Cl₂(g)  SiCl₄(g)
-657
SiCl₄(g) + 2Mg(s)  2MgCl₂(s) + Si(s)
-625

• A) +1972 kJ
• B) -1972 kJ
• C) -592 kJ
• D) +592 kJ
• E) -625 kJ

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Definitions:

Asset Account

A record in the financial statements that shows the value of a company's assets, including current, fixed, tangible, and intangible assets.

Liability Accounts

Financial accounting ledgers that record amounts owed to creditors or suppliers.

Debits

Accounting entries that increase asset or expense accounts, or decrease liability, equity, or revenue accounts.

Trial Balance

A bookkeeping worksheet in which the balances of all ledgers are compiled into debit and credit columns to ensure a company's bookkeeping system is mathematically correct.