Thermometry..HELP PLEASE..!!!?

Question

1] What is the temperature at which H2O [water] has maximum density.

2] A constant pressure air thermometer gave a reading of 47.5 units of volume when immersed in ice cold water, and 67 units in a boiling liquid. What is the boiling point of the liqiud?

Answer 1

Question 1:

You are referring to the unusual behaviour of water.

Matter expand when heated, and contract when cooled. But when you cooled water down until 4 degree C, it will actually be at its minimum volume. From 4 to 0 degree C, water actually expands ie its volume increases.

So at 4 degree C, its volume is a minimum, and since mass is constant, using the density formula, its density will be a maximum.

Question 2:

Temperature of ice cold water, T1 = 0 degree C = 273 K

Volume at ice cold water, V1 = 47.5 units

Let temperature of boiling liquid be T2.

Volume when in a boiling liquid, V2 = 67 units  

Using Charles Law, where pressure is constant,

V1 / T1 = V2 / T2

47.5 / 273 = 67 / T2

T2 = 385 K ( = 112 degree C)

Note that the temperature must be converted to its SI unit before you can use this formula to resolve the question, where 0 degree C = 273 K

Answer 2

1) It is approximately 4 degrees Celsius. That would be nearly 39 or 40 degrees F.

2) Use the formula V1 x T1 = V2 x T2 where T is the temperature in Kelvin and then convert that too Fahrenheit. By the way Kelvin is an absolute temperature scale.