Watchglass is a lab equipment that is used as a cover to prevent heated materials from splattering out of the container and as a holding plate for hot or flammable materials
<u>Explanation:</u>
Watch glass is an equipment used as a cover to prevent heated materials from splattering out of the container and as a holding plate for hot or flammable materials. It is a kind of concave glass which is also used to evaporate a liquid and also provides good air circulation which is used during cooking. The name watchglass was derived as they are see through and so similar to pocket glasses.
The frequency of the wave is 4 Hz
Answer:
55.96kJ
Explanation:
Energy = mass of diethyl ether × enthalpy of vaporization of diethyl ether
Volume (v) = 200mL, density (d) = 0.7138g/mL
Mass = d × v = 0.7138 × 200 = 142.76g
Enthalpy of vaporization of diethyl ether = 29kJ/mol
MW of diethyl ether (C2H5)2O = 74g/mol
Enthalpy in kJ/g = 29kJ/mol ÷ 74g/mol = 0.392kJ/g
Energy = 142.76g × 0.392kJ/g = 55.96kJ
