Calcium hydroxide, which reacts with carbon dioxide to form calcium carbonate, was used by the ancient romans as mortar in stone structures. the reaction for this process is ca(oh)2(s) + co2(g) → caco3(s) + h2o(g) δh = –69.1 kj what is the enthalpy change if 3.8 mol of calcium carbonate is formed?

-262.58 kJ

Explanation:

The enthalpy represents the energy that is either absorbed or released during a chemical reaction.  

We see that the chemical reaction that we have is balanced and 1 mol of calcium carbonate was formed. During this process -69.1 kJ or energy was released because it has a negative sign. We can say that the enthalpy changes  is -69.1kJ per every mol of calcium carbonate formed.  

Using a simple rule of three we can get the enthalpy change when 3.8 mol of are formed.

-69.1 Kj --- > 1 mol of  

X         --- >  3.8 mol of

So, the energy released when 3.8 mol of calcium carbonate are formed is -262.58 kJ.  

the best answer is d because the strong cohesion is caused by the ability of water molecules to undergo hydrogen bonding.

a is incorrect because when water solidifies, it becomes   ice, which expands and occupies a bigger volume for the same mass of water in its liquid state.

b is incorrect because water has high surface tension. besides bonding to itself it hydrogen bonds to other molecules at the top decreasing possibility for breaking of attractive forces.

c is incorrect because the water molecule has oxygen which is highly electronegative and so pulls the electron pair towards itself creating a dipole moment, making the molecule polar.

e is incorrect because water has strong adhesion, ability to stick to other molecules such as glass because of this molecules having stronger hydrogen bonding than water.