A)Calculate the mass of NaNO3 that heated strongly and produced 4.5 dm3(cubic decimeter) of O2 gas. The chemical equation for a chemical reaction is given below (2)
2NaNO3 ---> 2NaNO2 +O2
b) Calculate the concentration of HCl solution formed by dissolving 200 g HCl in 300 CM3 of water.(2)

a) 34 g

b) 18.33 moldm^-3

Explanation:

a) The equation of the reaction is;

2NaNO3> 2NaNO2 + O2

Let us recall that 1 mole of a gas occupies 22.4 dm^3. Since 1 mole of O2 is produced in the reaction, we can write;

2 moles of NaNO3 yields 22.4 dm^3 of O2

x moles of O2 yields 4.5 dm^3 of O2

x = 2 * 4.5/22.4

x = 0.4 moles of NaNO3

But number of moles = mass/molar mass

molar mass of NaNO3 = 85 g/mol

Mass of NaNO3 = 0.4 moles * 85 g/mol

Mass of NaNO3 = 34 g

b)

Number of moles in 200g of HCl = mass/molar mass

molar mass of HCl = 36.5 g/mol

Number of moles = 200g/36.5 = 5.5 moles

From;

Number of moles = concentration * volume in dm^3

concentration = Number of moles/ volume in dm^3

But volume = 300 cm^3 or 0.3 dm^3

concentration = 5.5/0.3 = 18.33 moldm^-3

i just learnt this recently but i need to look through my notes again

the earth would become to overheated and everything alive on it will eventually die from overheating. plants will eventually die as well, water will evaporate, and it will be nothing but a hot planet without anything living on it.