How much energy is needed to raise the temperature of [tex][tex]$10 g$[/tex][/tex] of iron compared to [tex][tex]$10 g$[/tex][/tex] of aluminum, each by [tex][tex]$1^{\circ} C$[/tex][/tex]?

[tex]\[
C_{ Fe }=0.450 \frac{ J }{ g \cdot{ }^{\circ} C } \quad C _{ Al }=0.900 \frac{ J }{ g \cdot{ }^{\circ} C }
\][/tex]

A. Fe needs twice as much energy as Al
B. Fe needs 0.450 times more energy than Al
C. Fe needs 0.450 times less energy than Al
D. Fe needs half as much energy as Al



Answer :

To determine the amount of energy required to raise the temperature of 10 grams of iron and 10 grams of aluminum by [tex]\(1^{\circ} C\)[/tex], we can use the heat energy formula:

[tex]\[ Q = m \cdot c \cdot \Delta T \][/tex]

where:
- [tex]\( Q \)[/tex] is the heat energy.
- [tex]\( m \)[/tex] is the mass.
- [tex]\( c \)[/tex] is the specific heat capacity.
- [tex]\( \Delta T \)[/tex] is the temperature change.

Given:
- Mass of iron ([tex]\( m_{Fe} \)[/tex]) = [tex]\( 10 \)[/tex] grams
- Mass of aluminum ([tex]\( m_{Al} \)[/tex]) = [tex]\( 10 \)[/tex] grams
- Temperature change ([tex]\( \Delta T \)[/tex]) = [tex]\( 1^{\circ} C \)[/tex]
- Specific heat capacity of iron ([tex]\( c_{Fe} \)[/tex]) = [tex]\( 0.450 \frac{ J }{ g \cdot{ }^{\circ} C } \)[/tex]
- Specific heat capacity of aluminum ([tex]\( c_{Al} \)[/tex]) = [tex]\( 0.900 \frac{ J }{ g \cdot{ }^{\circ} C } \)[/tex]

First, calculate the energy needed to raise the temperature of iron:

[tex]\[ Q_{Fe} = m_{Fe} \cdot c_{Fe} \cdot \Delta T \][/tex]
[tex]\[ Q_{Fe} = 10 \, \text{g} \cdot 0.450 \, \frac{ \text{J} }{ \text{g} \cdot ^{\circ} \text{C} } \cdot 1\, ^{\circ} \text{C} \][/tex]
[tex]\[ Q_{Fe} = 4.5 \, \text{J} \][/tex]

Next, calculate the energy needed to raise the temperature of aluminum:

[tex]\[ Q_{Al} = m_{Al} \cdot c_{Al} \cdot \Delta T \][/tex]
[tex]\[ Q_{Al} = 10 \, \text{g} \cdot 0.900 \, \frac{ \text{J} }{ \text{g} \cdot ^{\circ} \text{C} } \cdot 1\, ^{\circ} \text{C} \][/tex]
[tex]\[ Q_{Al} = 9.0 \, \text{J} \][/tex]

Now, we compare the energy required for iron and aluminum. The ratio of the energy needed for iron to the energy needed for aluminum is:

[tex]\[ \text{Energy ratio} = \frac{Q_{Fe}}{Q_{Al}} \][/tex]
[tex]\[ \text{Energy ratio} = \frac{4.5 \, \text{J}}{9.0 \, \text{J}} \][/tex]
[tex]\[ \text{Energy ratio} = 0.5 \][/tex]

This means that iron needs half as much energy as aluminum to raise the temperature of 10 grams by [tex]\(1^{\circ} C\)[/tex]. Therefore, the correct answer is:

D. Fe needs half as much energy as Al