Un casquillo de cobre de 8 kilogramos tiene que calentarse de 25 a 140 grados Celsius con el fin de expandirlo pata que se ajuste sobre un eje. ¿Cuanto calor se requirió?

354200J

Explanation:

Given parameters:

Mass of copper bushing = 8kg

Initial temperature  = 25°C

Final temperature  = 140°C

Unknown:

Quantity of heat required to heat this mass = ?

Solution:

The amount of heat required to heat mass from one temperature to another is given by;

                  H = m c Δt

where m is the mass

          c  is the specific heat

        Δt is the change in temperature

C is a constant and for copper, its value is 385J/kg°C

 Input the parameters;

            H = 8 x 385 x (140 - 25) = 354200J

  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 total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)