Math  /  Algebra

QuestionCalculate the energy required to heat 122.0 mg of ethanol from 3.1C-3.1^{\circ} \mathrm{C} to 17.3C17.3{ }^{\circ} \mathrm{C}. Assume the specific heat capacity of ethanol under these conditions is 2.44 J g1 K12.44 \mathrm{~J} \cdot \mathrm{~g}^{-1} \cdot \mathrm{~K}^{-1}. Round your answer to 3 significant digits.

Studdy Solution

STEP 1

What is this asking? How much energy do we need to warm up this little bit of ethanol? Watch out! Don't forget to convert milligrams to grams and Celsius to Kelvin!
Also, keep track of your units throughout the calculation.

STEP 2

1. Convert units
2. Calculate the change in temperature
3. Calculate the energy required

STEP 3

Alright, let's **convert** the mass of ethanol from milligrams to grams because the specific heat capacity is given in joules per *gram* Kelvin.
We're given 122.0122.0 mg of ethanol.
Since there are 10001000 mg in 11 g, we **divide** 122.0122.0 by 10001000 to get 0.12200.1220 g.
See? Easy peasy!

STEP 4

Now, let's **convert** those Celsius temperatures to Kelvin.
Remember, to go from Celsius to Kelvin, we just **add** 273.15273.15 to the Celsius temperature.
So, our **initial temperature** of 3.1C-3.1^\circ \mathrm{C} becomes 3.1+273.15=270.05K-3.1 + 273.15 = 270.05 \mathrm{K}.
And our **final temperature** of 17.3C17.3^\circ \mathrm{C} becomes 17.3+273.15=290.45K17.3 + 273.15 = 290.45 \mathrm{K}.

STEP 5

The **change in temperature**, represented by ΔT\Delta T, is simply the **final temperature** minus the **initial temperature**.
So, ΔT=290.45K270.05K=20.40K\Delta T = 290.45 \mathrm{K} - 270.05 \mathrm{K} = 20.40 \mathrm{K}.
That's how much our ethanol is warming up!

STEP 6

Now for the grand finale!
We can **calculate** the energy required (represented by qq) using the formula: q=mcΔTq = mc\Delta T, where mm is the mass, cc is the specific heat capacity, and ΔT\Delta T is the change in temperature.

STEP 7

Let's **plug in** our values: q=(0.1220 g)(2.44 Jg1K1)(20.40K)q = (0.1220 \mathrm{~g}) \cdot (2.44 \mathrm{~J} \cdot \mathrm{g}^{-1} \cdot \mathrm{K}^{-1}) \cdot (20.40 \mathrm{K}).
Notice how the units of grams and Kelvin **divide to one**, leaving us with just joules, which is the unit of energy!

STEP 8

**Multiplying** these values, we get q=6.05832 Jq = 6.05832 \mathrm{~J}.

STEP 9

Finally, we need to **round** our answer to **3 significant digits**.
So, our **final answer** is 6.06 J6.06 \mathrm{~J}.
Boom!

STEP 10

The energy required to heat the ethanol is 6.06 J6.06 \mathrm{~J}.

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