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.