Match the following associations. 1. + δhexothermic endothermic 2. e2 < e¹exothermic endothermic 3. energy is absorbed exothermic endothermic 4. e2 > e¹exothermic endothermic .5- δhexothermic endothermic

Explanation:

When heat is absorbed by reactants in a chemical reaction then the reaction is known as endothermic reaction.

Whereas when heat is released by reactants in a chemical reaction then the reaction is known as exothermic reaction.

1. When is positive then it means heat is absorbed by reactants and reaction is endothermic.

2. When , this means energy of products is less than the energy of reactants. Therefore, it is exothermic in nature.

3. When energy is absorbed then reaction is endothermic.

4. When , this means energy of products is greater than the energy of reactants. Therefore, it is endothermic in nature.

5. When [tex]\Delta H is negative then it means heat is released by reactants and reaction is exothermic.

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.