the combustionof 1.0g of gasoline realises 11kcal of heat (Density of gasoline=0.74g/ml)
a)how many megajoules are realised when 1.0 gallon of gasoline burns?
b)when a color TV is on for 2 hours 300KJ are used. How long can a color TV runon the energy from 1.0 gallon of gasoline?
Convert 1.0 gallon gasoline to grams, then to kcal heat on combustion, then to joules and megajoules.
b)2hours x (kJ from part a/300) = ??
Not a clue
To answer these questions, we need to use some basic conversion factors and formulas. Let's start with question a):
a) To find out how many megajoules are realized when 1.0 gallon of gasoline burns, we need to do a few calculations:
First, we need to convert the given 1.0g to gallons using the density of gasoline:
Density of gasoline = 0.74g/ml
Therefore, 1.0g / 0.74g/ml = 1.35 ml (rounded to 2 decimal places)
Next, we need to convert the volume from milliliters to gallons. Since there are approximately 3785 ml in a gallon:
Volume of gasoline in gallons = 1.35 ml / 3785 ml/gallon ≈ 0.00036 gallons (rounded to 5 decimal places)
Now, we can calculate the number of kilocalories (kcal) released when 0.00036 gallons of gasoline burns:
Energy released = 0.00036 gallons * 11 kcal/g = 0.00396 kcal (rounded to 5 decimal places)
Finally, we convert kilocalories to megajoules. Since 1 kcal is approximately 4.184 KJ:
Energy released in megajoules = 0.00396 kcal * 4.184 KJ/kcal ≈ 0.0165 MJ (rounded to 4 decimal places)
Therefore, when 1.0 gallon of gasoline burns, approximately 0.0165 megajoules of heat are realized.
b) To determine how long a color TV can run on the energy from 1.0 gallon of gasoline, we can use the given information:
Energy used by the color TV = 300 KJ
Energy released when 1.0 gallon of gasoline burns = 0.0165 MJ (converted from part a)
To find out how long the TV can run, we divide the energy released by the energy used per hour:
Time duration = Energy released / Energy used per hour
First, let's convert 0.0165 MJ to KJ by multiplying it by 1000:
Energy released in KJ = 0.0165 MJ * 1000 KJ/MJ = 16.5 KJ
Now, we divide the energy released by the energy used per hour:
Time duration = 16.5 KJ / 300 KJ/h = 0.055 hours
Therefore, a color TV can run for approximately 0.055 hours (or 3 minutes and 18 seconds) on the energy from 1.0 gallon of gasoline.