Question

The compound adrenaline contains \(56.79 \% \mathrm{C}, 6.56 \% \mathrm{H}\) , \(28.37 \% \mathrm{O},\) and 8.28\(\% \mathrm{N}\) by mass. What is the empirical formula for adrenaline?

Short answer

The empirical formula for adrenaline is C\(_{8}\)H\(_{11}\)O\(_{3}\)N.

Step-by-step solution

Calculate the moles of each element

Since we are given the mass percentages for each element, we can assume a 100g sample of adrenaline. In this sample, the mass of each element will exactly match the given mass percentage. Now, we need to calculate the moles of each element in our 100g sample using their molar masses. - For Carbon (C), molar mass = 12.01 g/mol - For Hydrogen (H), molar mass = 1.01 g/mol - For Oxygen (O), molar mass = 16.00 g/mol - For Nitrogen (N), molar mass = 14.01 g/mol

Convert the mass percentages to moles

Using the molar masses, we can calculate the moles of each element in a 100g sample of adrenaline: - Moles of Carbon (C) = \(\frac{56.79\,g}{12.01\,g/mol} = 4.730\,mol\) - Moles of Hydrogen (H) = \(\frac{6.56\,g}{1.01\,g/mol} = 6.495\,mol\) - Moles of Oxygen (O) = \(\frac{28.37\,g}{16.00\,g/mol} = 1.773\,mol\) - Moles of Nitrogen (N) = \(\frac{8.28\,g}{14.01\,g/mol} = 0.5910\,mol\)

Find the ratio of moles

To find the simplest whole number ratio, we need to divide each value of moles by the smallest number of moles among all the elements. In this case, the smallest number of moles is that of Nitrogen (N), which is 0.5910. - Ratio of Carbon (C) = \(\frac{4.730}{0.5910} = 8.000\) - Ratio of Hydrogen (H) = \(\frac{6.495}{0.5910} = 11.00\) - Ratio of Oxygen (O) = \(\frac{1.773}{0.5910} = 3.000\) - Ratio of Nitrogen (N) = \(\frac{0.5910}{0.5910} = 1.000\)

Determine the empirical formula

Now that we have found the simplest whole number ratio of the elements, we can write the empirical formula for adrenaline. The empirical formula is C\(_{8}\)H\(_{11}\)O\(_{3}\)N.

Key concepts

Percent Composition

The concept of percent composition is crucial in understanding the makeup of a compound. It tells us the percentage by mass of each element within a compound. For adrenaline, the percent composition is given as follows:

• Carbon (C): 56.79%
• Hydrogen (H): 6.56%
• Oxygen (O): 28.37%
• Nitrogen (N): 8.28%

To interpret this, one could assume a 100 gram sample of the compound for simplicity. In this way, the mass of each element in the sample aligns directly with its percentage. For instance, in a 100g sample, carbon would weigh 56.79g, since it constitutes 56.79% of the compound. Therefore, knowing the percent composition allows us to set up calculations to find out more about the chemical structure of the compound."

Mole Ratio

Mole ratio is a central concept when figuring out the empirical formula. After finding the moles of each element in the compound, the next step is to determine the smallest or simplest ratio between those moles. With adrenaline, the molar amounts were calculated and then divided by the smallest number of moles, which happened to be that of nitrogen. This step simplifies the values and allows representation in whole numbers.- Carbon (C): 4.730 moles- Hydrogen (H): 6.495 moles- Oxygen (O): 1.773 moles- Nitrogen (N): 0.5910 moles Given nitrogen's smallest mole value, all elements' moles can be divided by 0.5910. This calculation gives the simplest whole number ratio. It's this ratio that elucidates the empirical formula: - C: Ratio 8.000, Whole number 8- H: Ratio 11.00, Whole number 11- O: Ratio 3.000, Whole number 3- N: Ratio 1.000, Whole number 1Recognizing these ratios helps form the empirical formula C\(_{8}\)H\(_{11}\)O\(_{3}\)N.

Chemical Composition

Understanding chemical composition is key to deciphering any compound. It refers to the identities and proportions of the elements present within that compound. Adrenaline is made of carbon, hydrogen, oxygen, and nitrogen, as previously mentioned, with each holding specific percent compositions. These proportions offer insight into the makeup of the compound at the elemental level. Knowing the chemical composition helps in predicting properties and behaviors of the compound under various conditions. Moreover, chemical composition is the basis for further analysis, like determining the molecular formula or understanding reactivity patterns. By analyzing the elemental percentages and processing them into moles and ratios, we unfold the blueprint of adrenaline and solve for its empirical formula.

Adrenaline

Adrenaline, also known as epinephrine, is a hormone secreted by the adrenal glands. It plays a critical role in the "fight or flight" response by rapidly preparing the body to react to stressful situations. Chemically, adrenaline is composed primarily of carbon, hydrogen, oxygen, and nitrogen. Its empirical formula, derived through calculations of percent composition and mole ratios, is C\(_{8}\)H\(_{11}\)O\(_{3}\)N.Understanding the empirical formula of adrenaline not only helps in recognizing its structure, but also aids in grasping its chemical properties. This knowledge is essential for fields like pharmacology, where adrenaline is often synthesized and modified for medicinal uses.The empirical formula provides a simplified representation of the compound's composition and acts as a gateway to exploring its molecular identity and applications.