Question

In photosynthesis glucose ${{C}_{6}}{{H}_{12}}{{O}_{6}}$ and ${{O}_{2}}$ are produced from $C{{O}_{2}}$ and ${{H}_{2}}O$ .
$6C{{O}_{2}}\left( g \right)+6{{H}_{2}}O\left( l \right)+680kcal={{C}_{6}}{{H}_{12}}{{O}_{6}}\left( aq \right)+6{{O}_{2}}\left( g \right)$
How much heat in kilojoules is needed to produce 19.5g of ${{C}_{6}}{{H}_{12}}{{O}_{6}}$ ?

Answer 1

Photosynthesis is a process through which plants and other organisms transform light energy into chemical energy, which is then released to power the organism's metabolic processes through cellular respiration. Photosynthesis is the process of storing chemical energy in carbohydrate molecules like sugars and starches, which are made from carbon dioxide and water.

Complete answer:
Although various species execute photosynthesis in different ways, the process always starts with light energy being absorbed by proteins called reaction centres, which contain green chlorophyll pigments. These proteins are stored in chloroplasts, which are most numerous in leaf cells in plants, whereas they are embedded in the plasma membrane in bacteria.
The mole is the International System of Units' basic unit of material quantity (SI). It is defined as a collection of precisely $6.02214076\times {{10}^{23}}$ particles, which may be atoms, molecules, ions, or electrons. The Avogadro number ( $6.02214076\times {{10}^{23}}$ ) was set such that the mass of one mole of a chemical compound in grams is numerically equivalent to the average mass of one molecule of the compound in daltons for most practical applications.
$\text{Number of moles = }\dfrac{\text{Given mass}}{\text{Molar mass}}$
The molar mass of any element may be Now upon calculated by looking up the element's atomic mass on the periodic table.
Consider $6C{{O}_{2}}\left( g \right)+6{{H}_{2}}O\left( l \right)+680kcal={{C}_{6}}{{H}_{12}}{{O}_{6}}\left( aq \right)+6{{O}_{2}}\left( g \right)$
The stages in this question's computation will be as follows:
To convert grams of glucose to moles of glucose, use the formula below.
Now upon calculating the number of kilocalories in a mole of glucose.
Now upon calculating the difference between kilocalories and kilojoules.
1. Now upon calculating moles of glucose
Moles of glucose $=19.5 \mathrm{~g}$ glucose $\times \dfrac{1 \mathrm{~mol} \text { glucose }}{180.16 \mathrm{~g} \text { glucose }}=0.1082 \mathrm{~mol}$ glucose
2. Now upon calculating kilocalories
Kilocalories $=0.1082$ mol glucose $\times \dfrac{680 \mathrm{kcal}}{1 \text { mol glucose }}=73.60 \mathrm{kcal}$
3. Convert kilocalories to kilojoules using the conversion factor 1 kcal = 4.184 Joule
Kilojoules $=73.60$ kcal $\times \dfrac{4.184~\text{kJ}}{1\text{ kcal }}=308~\text{kJ}$
Hence 308kJ is the correct answer.

Note:
In the process of carbon fixation, carbon dioxide is transformed into sugars; photosynthesis uses energy from the sun to convert carbon dioxide into carbohydrate. Carbon fixation is a redox process that is endothermic. Photosynthesis is the polar opposite of cellular respiration in that it involves the conversion of carbon dioxide to carbohydrate, whereas cellular respiration involves the oxidation of carbohydrate or other nutrients to carbon dioxide. Carbohydrates, amino acids, and fatty acids are among the nutrients needed in cellular respiration.