Question

The volumes of gases A, B, C, and D are in this ratio $1:2:2:4$ under the same conditions of temperature and pressure. If the volume of A is actually $5.6{\mathrm{dm}}^3$ at STP, calculate the number of molecules in the actual volume of D at STP (Avogadro's number is $6\times {10}^{23}$). The volume of D is four times the volume of A as given.

Answer 1

Step 1: Given data

The ratio of volume of gases A, B, C, D$=1:2:2:4$

The volume of A at STP$=5.6{\mathrm{dm}}^3$

Avagadro's number$=6\times {10}^{23}$

The volume of D is four times A

Step 2: Calculating the number of molecules of D at STP

According to the question, the Volume of D is equal to four times the volume of A.

The volume of D$=4\times$ Volume of A

The volume of D $=4\times 5.6\Rightarrow 22.4{\mathrm{dm}}^3$

Since the volume is equal to the volume present at standard temperature and pressure, $22.4{\mathrm{dm}}^3$ will have $6\times {10}^{23}$molecules.

Therefore, the number of molecules in the actual volume of D at STP is $6\times {10}^{23}$