A warm front is heading toward Chicago. Which type of weather would one expect when it arrives?
2 answers:
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Answer: B) 46.7% Si and 53.3% O
Explanation:
To calculate the mass percent of element in a given compound, we use the formula:
Mass of quartz = 5.05 g
Mass of silicon = 2.36 g
Mass of oxygen = Mass of quartz - mass of silicon = 5.05g - 2.36 g = 2.69 g
Thus the percentages of silicon and oxygen in quartz are B) 46.7% Si and 53.3% O
Answer: The standard enthalpy change for this reaction is -116 kJ
Explanation:
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The given chemical reaction is,
Now we have to determine the value of for the following reaction i.e,
According to the Hess’s law, if we reverse the reaction then the will change its sign and if we half the reaction, then the
So, the value for the reaction will be:
Hence, the standard enthalpy change for this reaction is -116 kJ