Our subjective feeling of hot and cold depends on the rate at which heat is lost through our skin. in this problem, we will model the skin as a flat layer of fatty tissue (k 0.3 w/m °k) with a thickness of 4 mm, separating an environment with a constant temperature of 37°c (normal body temperature) and the outside air. on a calm winter day with an ambient temperature of 0'°c, the convective heat transfer coefficient between the skin and the ambient air is approximately equal to 20 w/m2 °k. find the heat flux lost through the skin.

q = 2.343 W/m^2

Explanation:

Given data:

Ambient temperature =  0°C

Normal Body temperature = 37 °C

Thermal conductivity of tissue is K 0.3W/m °K

Heat transfer coefficient 20 W/m2 °K

Heat flux can be determined by using following formula

putting all value to get flux value

q = 2.343 W/m^2

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.