5.
a 120.0 g sample of thallium-208 decays. how much of the sample will remain after 3 half lifest

15.0 g

We are given;

We are required to calculate the remaining mass after three half lives

N = N₀ × 0.5^n

where, N is the remaining mass, N₀ is the original mass and n is the number of half lives.

Therefore;

N = 120.0 g × 0.5^3

  = 15.0 g

Thus, the remaining mass of Thallium-208 is 15.0 g

Alternatively;

120.0 g → 60.0 g (120 × 0.5) → 30.0 g (60 × 0.5) → 15.0 g (30 × 0.5)

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).

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante