Select the correct answer.
carbon burns in the presence of oxygen to give carbon dioxide. which chemical equation describes this reaction?
a. carbon + oxygen + carbon dioxide
b.
carbon + oxygen - carbon dioxide
oc
carbo
carbon dioxide - carbon + oxygen
d.
carbon dioxide + carbon - oxygen
reset
next

When carbon burns in the presence of oxygen to give carbon dioxide the correct chemical equation which describe this reaction is carbon + oxygen - carbon dioxide.

Hence the correct answer to the above question is option b.

Explanation:

Carbon dioxide is of gaseous state. The formula which represent carbon dioxide is  CO2. The carbon dioxide is formed when an element which has carbon in it burns in the “presence of oxygen”.

The black gas released while burning this is known as carbon dioxide. Carbon dioxide is very helpful for the plant for the process of photosynthesis for preparing their food in the presence of sunlight and water.

Question:

A piston–cylinder device contains 0.85 kg of refrigerant- 134a at -10°C. The piston that is free to move has a mass of 12 kg and a diameter of 25 cm. The local atmospheric pressure is 88 kPa. Now, heat is transferred to refrigerant-134a until the temperature is 15°C. Determine (a) the final pressure, (b) the change in the volume of the cylinder, and (c) the change in the enthalpy of the refrigerant-134a.

a) 90.4 kPa

b) 0.0205 m³

c) 17.4 kJ/kg

Explanation:

Given:

Mass, m = 0.85 kg

a) The final pressure here is equal to the initial pressure. Let's use the formula:

= 90398 Pa

≈ 90.4 KPa

Final pressure = 90.4 kPa

b) Change in volume of the cylinder:

To find the initial and final volume, let's use the values from the A-13 table for refrigerant-134a, at initial values of 90.4 kPa and -10°C and final values of 90.4 kPa and 15°C

v1 = 0.2302m³/kg

h1 = 247.76 kJ/kg

v2 = 0.2544 m³/kg

h2 = 268.2 kJ/kg

Change in volume is calculated as:

Δv = m(v2 - v1)

Δv = 0.85(0.2544 - 0.2302)

= 0.0205 m³

Change in volume = 0.0205 m³

c) Change in enthalpy

Let's use the formula:

Δh = m(h2 - h1)

= 0.85(268.2 - 247.76)

= 17.4 kJ/kg

Change in enthalpy = 17.4 kJ/kg