The correct answer among the choices given is option B. The one that describes a proper use of eyeglasses is that using diverging lenses to help a nearsighted person by moving the image from in front of the retina to the retina. For this, t<span>he lenses will diverge the light before it reach the eye and aim it to the retina, correcting our nearsighted visual.</span>
Close to about -36 degrees Celsius ( - 33 degrees Fahrenheit) in January but can drop to -60 degrees Celsius ( - 76 degrees Fahrenheit).
in July, it can be close to -19 degrees Celsius (- 2 degrees Fahrenheit)
Answer:
(a) The amount of O2 needed is 2.67 pounds.
(b) The volume required is 847,509 litres.
(c) The heat given off as a result of the combustion to CO2 is 393.5 kJ.
Explanation:
For a complete combustion of C to C02(g)
![C+O_{2} \rightarrow CO_{2}](https://tex.z-dn.net/?f=C%2BO_%7B2%7D%20%5Crightarrow%20%20CO_%7B2%7D)
(a) The molecular mass of O2 is 32 g/mol and the molecular mass of C is 12 g/mol.
We need 1 mol O2 to burn 1 mol of C.
If we need 32 g of O2 to burn 12 g of C, to burn 1 pound of pure carbon charcoal we need (32/12)*1=2.67 pounds of O2.
(b) The density of O2, at atmospheric conditions, is 1.429 g/l. The volume of 2.67 pounds of O2 is
![V=M/\rho=(2.67 lb)*(\frac{1 l}{1.429 g})*(\frac{453,592 g}{1lb}) =\frac{1,211,090}{1.429}= 847,509 l](https://tex.z-dn.net/?f=V%3DM%2F%5Crho%3D%282.67%20%20lb%29%2A%28%5Cfrac%7B1%20l%7D%7B1.429%20g%7D%29%2A%28%5Cfrac%7B453%2C592%20g%7D%7B1lb%7D%29%20%3D%5Cfrac%7B1%2C211%2C090%7D%7B1.429%7D%3D%20847%2C509%20l)
(c) To calculate the heat of the reaction, we have to look up in the Table of Standard Enthalpy of Formation Values and compute the following equation
![\Delta H_{reaction}^{o}=\sum\Delta H_{f}^{o} (products)-\sum\Delta H_{f}^{o}(reactants)\\\\\Delta H_{reaction}^{o}=\Delta H_{f CO_{2}}^{o}-(\Delta H_{fO_{2}}^{o}+\Delta H_{fC}^{o})\\\\\Delta H_{reaction}^{o}=(1 mol) *(-393.5 kJ/mol)-((1mol)*(0 kJ/mol)+(1mol)*(0 kJ/mol))\\\\\Delta H_{reaction}^{o}=-393.5 kJ](https://tex.z-dn.net/?f=%5CDelta%20H_%7Breaction%7D%5E%7Bo%7D%3D%5Csum%5CDelta%20H_%7Bf%7D%5E%7Bo%7D%20%28products%29-%5Csum%5CDelta%20H_%7Bf%7D%5E%7Bo%7D%28reactants%29%5C%5C%5C%5C%5CDelta%20H_%7Breaction%7D%5E%7Bo%7D%3D%5CDelta%20H_%7Bf%20CO_%7B2%7D%7D%5E%7Bo%7D-%28%5CDelta%20H_%7BfO_%7B2%7D%7D%5E%7Bo%7D%2B%5CDelta%20H_%7BfC%7D%5E%7Bo%7D%29%5C%5C%5C%5C%5CDelta%20H_%7Breaction%7D%5E%7Bo%7D%3D%281%20mol%29%20%2A%28-393.5%20kJ%2Fmol%29-%28%281mol%29%2A%280%20kJ%2Fmol%29%2B%281mol%29%2A%280%20kJ%2Fmol%29%29%5C%5C%5C%5C%5CDelta%20H_%7Breaction%7D%5E%7Bo%7D%3D-393.5%20kJ)
The heat given off as a result of the combustion to CO2 is 393.5 kJ.
Mass is the amount of matter in an object.