In a thermochemistry experiment the reaction of 0.0857 g of an unknown metal and an excess of 4.0 M HCl resulted in a 0.210 mL decrease in the volume of an ice/water mixture. Calculate the enthalpy of this reaction per 1 g of metal reacted. Needed data:

density of water at 273 K = 1.00 g/ml
density of ice at this temperature = 0.917 g/mL
ice enthalpy of fusion = 333 J/g

what is the correct answer ?

45 16 mol/L

-9.02kj

haha anon.

0.723kJ

To calculate the enthalpy of the reaction per 1 g of metal reacted, we need to determine the amount of heat transferred during the reaction and divide it by the number of grams of metal reacted.

First, let's determine the heat transferred during the reaction using the volume change of the ice/water mixture. We can use the following equation:

q = m * ΔH
where q is the heat transferred, m is the mass, and ΔH is the enthalpy change.

Given:
- Volume change of the ice/water mixture = 0.210 mL
- Density of water at 273 K = 1.00 g/mL
- Density of ice at 273 K = 0.917 g/mL
- Ice enthalpy of fusion = 333 J/g

To find the mass change, we need to convert the volume change to mass change by using the densities of water and ice.

Mass change = Volume change * Density of water = 0.210 mL * 1.00 g/mL = 0.210 g

Since the density of ice is different, we need to correct for the volume change when it freezes.
Mass change = Mass change - Volume change * Density of ice when freezing = 0.210 g - 0.210 mL * 0.917 g/mL = 0.210 g - 0.192 g = 0.018 g

Now, we can calculate the heat transferred during the reaction using the mass change and the enthalpy of fusion of ice:

q = mass change * ΔH = 0.018 g * 333 J/g = 5.94 J

The heat transferred during the reaction is 5.94 J.

To calculate the enthalpy change per 1 g of metal reacted, we need to divide the heat transferred by the mass of the metal reacted:

Enthalpy change per 1 g of metal reacted = q / mass of metal reacted

Given:
- Mass of metal reacted = 0.0857 g

Enthalpy change per 1 g of metal reacted = 5.94 J / 0.0857 g = 69.3 J/g

Therefore, the enthalpy change per 1 g of metal reacted is 69.3 J/g.