Ethanol is added to gasoline because the oxygen it contains improves gasoline's burning efficiency. its combustion reaction is given below. ch3ch2oh(l) 3o2(g) → 2co2(g) 3h2o(g) ∆h
a) is this an exothermic or endothermic reaction? b) if 15.3 grams of pure ethanol is completely converted to products, calculate how much heat is absorbed or released, in (1) kj and in (2) kcal. c) if 42.7 g of water vapor is produced, how much heat, in kl, is absorbed or released?

radioactive decay occurs in unstable atomic nuclei – that is, ones that don't have enough binding energy to hold

the nucleus together due to an excess of either protons or neutrons.

answer: -

reaction:

na + cl ⇌ nacl

balanced chemical equation:

na + 2cl ⇌ nacl2

sodium + clorine goes to form sodium chloride (table salt).

the product is nacl2.

and the reactants are na and cl.

(note: if you don’t know what ⇌ means, read below: -

⇌(double head arrow) means reversible reaction).

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3

the answer is 75.0%.