20,345
edits
Changes
no edit summary
| style="height:20px; width:300px; text-align:left;" |The increase [[Internal Energy|internal energy]] during the [[time]] when the [[temperature]] remains constant is the [[energy]] required to [[melt]] the [[material]]. This can be used to calculate the [[Specific Latent Heat of Fusion|'''specific latent heat''' of fusion]].
| style="height:20px; width:300px; text-align:left;" |The increase [[Internal Energy|internal energy]] during the [[time]] when the [[temperature]] remains constant is the [[energy]] required to [[boil|vaporise]] the [[material]]. This can be used to calculate the [[Specific Latent Heat of Vaporisation|'''specific latent heat''' of vaporisation]].
|}
===Equation===
''NB: You do not need to remember this equation but you need to be able to use it.''
Specific Latent Heat = (Energy Transferred)/(Mass)
<math>L = \frac{E}{m}</math>
Where:
<math>L</math> = The [[Specific Latent Heat]] of the [[material]].
<math>E</math> = The [[Energy]] [[Energy Transfer|transferred]] to the [[material]] during the [[State Change|state change]].
<math>m</math> = The [[mass]] of the [[material]].
===Example Calculations===
{| class="wikitable"
| style="height:20px; width:300px; text-align:center;" |An 11kg block of [[ice]] at 0°C is [[heat]]ed by an [[Immersion Heater|immersion heater]] until it completely [[melting|melts]]. The [[Immersion Heater|immersion heater]] is connected to a [[Joulemeter]] which reads 3.7MJ. Calculate the [[Specific Latent Heat of Fusion|'''specific latent heat''' of fusion]] of the [[water]] [[ice]] correct to two [[Significant Figures|significant figures]].
| style="height:20px; width:300px; text-align:center;" |A pan containing 500g of [[water]] at 100°C is [[heat]]ed with an [[energy]] of 1.13kJ until all of the [[water]] has been vaporised. Calculate the [[Specific Latent Heat of Vaporisation|'''specific latent heat''' of vaporisation]] of the [[water]] [[steam]] correct to two [[Significant Figures|significant figures]].
|-
| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantities in [[SI Unit]]s'''
E = 3.7MJ = 3.7x10<sup>6</sup>J
m = 11kg
| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantities in [[SI Unit]]s'''
E = 1.13kJ = 1.13x10<sup>3</sup>J
m = 500g = 0.5kg
|-
| style="height:20px; width:300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
<math>L_f = \frac{E}{m}</math>
<math>L_f = \frac{3.7 \times 10^6}{11}</math>
<math>L_f = 3.36363 \times 10^5 J/kg</math>
<math>L_f \approx 3.4x10^5 J/kg</math>
| style="height:20px; width:300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
<math>L_v = \frac{E}{m}</math>
<math>L_v = \frac{1.13 \times 10^3}{0.5}</math>
<math>L_v = 2260 J/kg</math>
<math>L_v \approx 2300 J/kg</math>
|}