Awashing machine uses 1.8 × 105 watts of power. if it is in use for 2 hours per day (on average), how many kilowatt hours will it use in 30 days? a. 1.1 × 104 kilowatt hours b. 36 kilowatt hours c. 18 kilowatt hours d. 540 kilowatt hours e. 1.1 × 106 kilowatt hours

  the grams     of oxygen gas   that can be produced     is 20.6   grams of o₂

calculation

2liclo₃ →   2 licl + 3 o₂

step 1:   find the moles of liclo₃

moles = mass÷ molar mass

from periodic table the molar mass of liclo₃ =6.9 +35.5   +(16 x3) =90.4 g/mol

moles=38.7 g÷90.4 g/mol=0.4281   moles

step 2:   use the   mole ratio   to calculate the moles of o2

from equation above, liclo₃: o₂   is 2: 3  

therefore the moles of   o₂=0.4281 moles x3/2 =0.6422   moles

step 3: find mass   of o₂

mass= moles x molar mass

from periodic table the   molar mass of   o₂ = 16 x2= 32 g/mol

mass=0.6422   moles   x   32 g/mol = 20.6 grams of o₂

the amount of current in the coil

c. magnitude and direction

conservation of mass

mass before something happens = mass afterwards