If the van urk reagent is used to test a sample and it turns bluish-purple, what drug does this indicate the presence of?
1 answer:
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Answer:
1. A molecule
2. A mixture
3. Concentration
4. Chemical formula
5. Kinetic energy
Explanation:
1. A molecule consists of two or more different types of atoms bonded together.
For this question, it's important to understand that we cannot be too abstract and use terms, such as compound. The reason is simple: molecules consist of atoms, and while molecules produce compounds, the latter can also be ionic. Ionic compounds would contain ions in them rather than atoms. In ionic compounds, electrons are transferred from one atom to the other to form cations and anions.
Molecules, on the other hand, consist of atoms. In fact, those atoms shouldn't necessarily be different: for example, we may have an oxygen gas molecule which consists of two oxygen atoms.
2. A mixture is a combination of different substances that can be separated by physical means.
Usually, mixtures are in the same physical state, for example, we may have a mixture of an aqueous layer, such as water, and an organic layer, such as hexane. In order to separate them, we might use a separation funnel, as water is polar and hexane is non-polar, they will form two separate layers. Collecting the bottom layer in a separate flask from the funnel and then the remaining layer will help us separate them based on their difference in polarity.
3. Many variables in chemistry depend on the amount of water present. Water is a solvent. One of the typical examples is concentration. Concentration, or molarity, is a ratio between the moles of a solute and the volume of a solution. Changing the amount of water would change the concentration of a solute as a result.
E. g., if we evaporate water, our solvent, from a specific solution, the concentration of a solute will increase, as we'll have the same amount of a solute in moles for a lower volume of a solution. Similarly, if we dilute the solution (increase the volume of it by adding more water), the volume will increase and we'll have the same amount in moles of the solute for a greater amount of the solution, so the concentration will decrease.
4. A chemical formula has fixed definite proportions at all times. Regardless of what mass of a compound we have, according to the law of definite proportions, atoms always combine in a fixed ratio in compounds. For example, we know that we would always have two hydrogen atoms and one oxygen atom in a water molecule regardless of what mass of water we have.
Similarly, if we remember ionic compounds, if we take sodium chloride, NaCl, the ionic ratio between sodium and chloride ions is always 1 : 1 (one sodium cation combined with one chloride anion). This is fundamentally true and it's independent of any quantity.
5. Similarly, this is an open question. A typical answer to this would be kinetic energy. Kinetic energy only depends on temperature of a substance. Kinetic energy is the energy of movement: the greater it is, the greater the velocity of an object.
The greater the temperature, the higher the kinetic energy. This direct proportionality is seen from the equation , where k is a constant and T is the absolute temperature. Notice that for higher T values, the kinetic energy term is higher.
Thinking about it from the other perspective, density, as another example, also depends on temperature. The greater the temperature, the greater the distances between the molecules, so the density decreases with an increase in temperature.
There are many more thermodynamic examples to look at as well!