Answer:
The correct answer is:
<em>(1) It is important that the sample is dissolved in just enough hot solvent. </em>
Explanation:
The process of recrystallization is important to eliminate the impurities and to obtain better crystals of the solid. The solvent used to perform the recrystallization must have a high dissolution power of the substance to be recrystallized and a low dissolution power of the impurities. This is in order to eliminate most impurities. Furthermore, <em>It is important that the sample is dissolved in just enough hot solvent </em>because this should be easy to remove after the recrystallization and the crystal should form easily when the solution cools. Also, it is better to add the hot solvent to solubilize the crystals and keep the impurities insoluble, instead of adding the cold solvent and heating the solution. Additionally, the process of cooling the solution must be done slowly to obtain large and fewer crystals. A fast ice-cooling will form smaller crystals.
Answer: Double replacement reaction
Explanation:
Layla it is A. that's the only one in standard form.
Answer:
- Third choice:<em> energy present in the glucose and oxygen that is not needed for the formation of carbon dioxide and water is released to form energy/ATP.</em>
Explanation:
<u>1) Chemical equation (given):</u>
- C₆H₁₂O₆ + 6 O₂ --> 6 CO₂ + 6 H₂O + energy
<u>2) Chemical potential energy:</u>
Each compound stores chemical potential energy. This energy is stored in the chemical bonds.
Due to every substance has its own unique chemical potential energy, when a chemical reaction takes plase, yielding to the change of some substances, some energy is absorbed (when bonds are formed) and some energy is released (when bonds are broken).
<u>3) Conservation of energy:</u>
Then, if the sum of the bond energies of the final products is less than the sum of the bond energies of the reactants, the<em> law of conservation of energy</em> rules that the difference between the total energies of the products and reactants must be released to the surroundings.
That is what is happening in the given reaction:
- C₆H₁₂O₆ + 6 O₂ --> 6 CO₂ + 6 H₂O + energy
The term energy in the product side means that energy is conserved because it is being released due to the the glucose and oxygen (reactant side) have more energy stored in their bonds than the energy needed for the formation of carbon dioxide and water, so that excess of energy is released to form energy/ATP.
<u>Summarizing:</u>
- The energy on the product side added to the energy of carbon dioxide and water equals the energy of the glucose and oxygen and the final balance is:
- ∑ Energy of the reactants = ∑energy of the products + released energy, supporting the law of conservation of energy.
