Acertain substance x has a normal boiling point of 124.2 °c and a molal boiling point elevation constant k,-06-0c-kg-mol ·a solution is prepared by dissolving some urea ((n112)co) in 650. g ofl. this solution boils at 124.7 oc, calculate the mass of urea that was dissolved. be sure your answer has the correct number of significant digits. 31.48 g

32 g

Explanation:

The increase in the boiling point of X can be calculated using the following expression.

ΔT = Kb × b

where,

ΔT: increase in the boiling point

Kb: molal boiling point constant (0.62 °C.kg/mol) (I looked it on the web)

b: molality of the solute

ΔT = Kb × b

(124.7°C - 124.2°C) = (0.62 °C.kg/mol) × b

b = 0.81 mol/kg

The mass of X is 650 g (0.650 kg). Then, the moles of urea (solute) are:

The molar mass of urea is 60.06 g/mol. The mass of urea is:

1 is the answer to this problem

(newtons first law)

conservation of momentum law states :

momentum before collision = momentum after collision

momentum p (kg-m/s)= mass * velocity

say moving car=1 000 kg, velocity = 10 m/s then p = 1 000*10= 10 000 kg-m/s

say still car = 2 000 kg, velocity = 0 m/s then p = 2 000* 0 = 0 kg-m/s

total momentum prior to collision = 10 000 + 0 = 10 000 kg-m/s

momentum after collision = 10 000 kg-m/s

mass now = 1 000 kg+2 000 kg = 3 000 kg

10 000 = 3 000 kg* velocity m/s

10 000/3 000 = velocity

3.33 m/s = velocity after collision

an impulse is a force applied over time , momentum is exclusive of external forces and a perfect collision is implied