Problem 10 - Chemistry The Molecular Science

Question

Which of the these statements are qualitative? Which are quantitative? Explain your choice in each case. (a) The atomic mass of carbon is \(12.011(12.011\) atomic mass units). (b) Pure aluminum is a silvery-white metal that is nonmagnetic, has a low density, and does not produce sparks when struck. (c) Sodium has a density of \(0.968 \mathrm{~g} / \mathrm{mL}\). (d) In animals the sodium cation, \(\mathrm{Na}^{+}\), is the main extracellular cation and is important for nerve function.

Step-by-Step Solution

Answer

(a) and (c) are quantitative; (b) and (d) are qualitative.

Step 1: Understanding Qualitative vs Quantitative

First, we need to define the terms: Quantitative data relates to measurements and numbers (think 'quantity'), while qualitative data describes qualities or characteristics without numbers (think 'quality').

Step 2: Analyzing Statement (a)

Statement (a) 'The atomic mass of carbon is 12.011 atomic mass units' involves a numerical value, which makes it quantitative. This statement provides a specific measurement of the carbon atom's mass.

Step 3: Analyzing Statement (b)

Statement (b) 'Pure aluminum is a silvery-white metal that is nonmagnetic, has a low density, and does not produce sparks when struck' describes the qualities and characteristics of aluminum without using numbers, thus it is a qualitative statement.

Step 4: Analyzing Statement (c)

Statement (c) 'Sodium has a density of 0.968 g/mL' gives us a numerical measure of sodium's density, which makes it quantitative. It specifies a quantity related to density.

Step 5: Analyzing Statement (d)

Statement (d) 'In animals, the sodium cation, Na+, is the main extracellular cation and is important for nerve function' provides information about the role and function of Na+ in animals, which is descriptive and not numerical, so it is qualitative.

Key Concepts

Atomic Mass

Every element on the periodic table has a specific atomic mass, which is a weighted average of the masses of its isotopes. Atomic mass is usually expressed in atomic mass units (amu), where one amu is defined as one twelfth of the mass of a carbon-12 atom. Carbon, for example, has an atomic mass of about 12.011 amu. This number indicates the average mass of carbon atoms, factoring in the relative abundance of each isotope of carbon found in nature. Atomic mass is crucial for understanding chemical reactions and stoichiometry because it helps predict how atoms will interact. For example, knowing the atomic mass allows chemists to compute molar mass, a key concept in quantifying and balancing chemical reactions.

Density

Density is a physical property of matter, defined as an object's mass per unit volume. The formula to calculate density is \( \rho = \frac{m}{V} \), where \( \rho \) (rho) is the density, \( m \) is the mass, and \( V \) is the volume. Considering density provides insight into how substances will behave in different environments.Sodium, a soft, silvery-white, highly reactive metal, has a density of 0.968 g/mL. This numeric value classifies it as a quantitative measure. Knowing the density of sodium is important in various applications, such as in predicting how it will interact with water and other substances, or even its role in biological systems.

Sodium Cation

The sodium cation, \( \mathrm{Na}^{+} \), is an essential electrolyte in many physiological processes. It plays a key role in maintaining blood pressure, nerve function, and muscle movement. Generally, sodium ions are found outside of cells, hence termed "extracellular."In animals, the regulation of sodium ions is vital for the transmission of electrical signals in the nervous system. The movement of these ions across cell membranes influences the conduction of nerve impulses. The qualitative aspects of sodium ions, such as their functional roles in biological systems, can be emphasized beyond just their numerical presence. Sodium cations are pivotal in electrolyte balance and overall bodily functions.

Aluminum Properties

Aluminum is a versatile metal known for its unique set of properties that make it valuable in various industries. It is lightweight, with a low density of approximately 2.7 g/cm³, making it ideal for applications where reducing weight is essential, such as in aerospace and automotive industries. The metal is silvery-white in appearance and exhibits nonmagnetic properties. Aluminum is also known for its ability not to produce sparks when struck, making it safer in flammable or explosive environments. Moreover, aluminum is malleable, corrosion-resistant, and a good conductor of electricity and heat. These qualitative characteristics highlight aluminum’s usefulness and adaptability across numerous environments and applications.