Hi. I'm trying to find the elemental composition of pure substances. Kahn Academy is telling me to multiply by 5 for this problem to find the answer. How do I know what integer to use? Question: "A sample of a compound containing only carbon and hydrogen atoms is completely combusted, producing 110.0 g C02 and 27.0 g H20. Find the empirical formula."

Hint 3 of 4: "Next, let’s find the simplest whole number ratio of atoms in the compound by dividing each of the mole values for carbon and hydrogen by the smallest of the two values. To obtain whole numbers, we also need to multiply by an integer:

C: 2.5/2.5 = 1 C x 5 = 5 carbons
H: 3.0/2.5 = 1.2 H x 5 = 6 hydrogens

​Where are the 5's above coming from?

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.

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.