Answer:
2994 kJ
Explanation:
When one mol of ethane (C₂H₆) is combusted, 1451 kJ of heat is exchanged.
First we convert 61.9 g of C₂H₆ into moles, using its molar mass:
- 61.9 g ÷ 30 g/mol = 2.06 mol C₂H₆
Finally we <u>calculate how much heat is exchanged by the combustion of 2.06 moles of C₂H₆</u>:
- 2.06 mol * 1451 kJ/mol = 2994 kJ
Answer:For a typical experiment, you should plan to repeat it at least three times (more is better).
Explanation:
Accurate data means the data experimentally obtained are close to the true value. Precise data means the data obtained are close to one another. In this case, the data are close to the true value which is 1.2 and the data are relatively close to one another. Hence the set is both accurate and precise.
The amount of substance present in a certain object with a given half-life in terms of h can be expressed through the equation,
A(t) = (A(o))(0.5)^(t/h)
where A(t) is the amount of substance after t years and A(o) is the original amount. In this item we are given that A(t)/A(o) is equal to 0.89. Substituting the known values,
0.89 = (0.5)(t / 5730 years)
The value of t from the equation is 963.34 years.
<em>Answer: 963 years</em>
