# 1.7: Problems

1.1. A Ford Focus produces 160 horsepower [16]. Calculate the power produced in watts, and calculate the approximate energy produced by the vehicle in one hour.

1.2. A gallon of gas contains $$1.21 \cdot 10^{5}$$ Btu and weighs 6 pounds [8]. Calculate the energy stored in the gallon of gas in joules, and calculate the specific energy in joules per kilogram.

1.3. An Oreo cookie has 53 food calories and weighs 11 grams [17]. A ton (2000 pounds) of TNT contains approximately $$4.184 \cdot 10^{9}$$ J of energy [7]. Calculate the specific energy of the cookie in joules per kilogram, and calculate the specific energy of the TNT in joules per kilogram. (Yes, the value for the cookie is higher.)

1.4. Find the electron configuration of an isolated indium atom in the lowest energy state. How many electrons are found around the atom? Repeat for a Cl$$^-$$ ion.

1.5. Use a periodic table for this problem.

(a) Which element has the electron configuration $$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{2}$$?

(b) List two elements which have exactly two valence electrons.