Answer:
The activation energy for an endothermic reaction is quite large and usually takes extra energy from the environment, it is normally not a natural spontaneous process.
Explanation:
- Endothermic reactions require absorbing energy of the surrounding mainly in the form of heat.
- Chemical energy needs energy input to break the bonds.
- Examples of endothermic reactions: Photosynthesis
, melting of ice
, and evaporating liquid water.
helium
has the most neutrons in the nucleus
Answer:
SrSO4
Explanation:
According to solubility rules, we know that the sulphates of the elements of group two are insoluble in water. The solubility rules describe what chemical species are soluble in water and what species are not soluble in water.
Generally, all chlorides are soluble in water with exception of chlorides such as silver chloride. The chlorides of group one elements are usually highly soluble in water.
Since SrSO4 is a sulphate of a group two element (strontium) it will be the insoluble solid product of the double displacement reaction described in the question.
<h3>
Answer:</h3>
= 5.79 × 10^19 molecules
<h3>
Explanation:</h3>
The molar mass of the compound is 312 g/mol
Mass of the compound is 30.0 mg equivalent to 0.030 g (1 g = 1000 mg)
We are required to calculate the number of molecules present
We will use the following steps;
<h3>Step 1: Calculate the number of moles of the compound </h3>
Therefore;
Moles of the compound will be;
= 9.615 × 10⁻5 mole
<h3>Step 2: Calculate the number of molecules present </h3>
Using the Avogadro's constant, 6.022 × 10^23
1 mole of a compound contains 6.022 × 10^23 molecules
Therefore;
9.615 × 10⁻5 moles of the compound will have ;
= 9.615 × 10⁻5 moles × 6.022 × 10^23 molecules
= 5.79 × 10^19 molecules
Therefore the compound contains 5.79 × 10^19 molecules
