11. If there are 8.24 x 1022 molecules of NaCl in a salt shaker, what is the mass of the salt?

Oxygen's mass percent in Fe(OH)3 is 44.92%

Explanation: The mass percentage is a means of indicating the concentration of a specific element within a compound. It is determined through the ratio of the element's mass to the compound's total mass, multiplied by 100.

•First calculate the overall mass of the compound

•Fe's molar mass = 55.85 g/mol

•O's molar mass = 16 g/mol

•H's molar mass = 1 g/mol

Using these values, we can compute the molecular mass of Fe(OH)3 = 55.85 g/mol + (16 g/mol)3 + (1 g/mol)3

=55.85 g/mol + 48 g/mol + 3 g/mol

=106.85 g/mol

Mass percent of an element = mass of element/total mass of compound × 100

In the case of 3 oxygen atoms present within the compound, the mass of oxygen totals 48 g/mol

Mass percent of oxygen= 48 g/mol/106.85 g/mol × 100

= 0.4492×100= 44.92%

Response:

q < 0, w > 0, the sign of ΔE cannot be ascertained from the provided details

Explanation:

Assessing the sign of q

The water bath's temperature before the reaction is at 25 °C

Following the reaction, the water bath's temperature rises to 28 °C, suggesting that heat was released from the system during the reaction.

If heat is absorbed by the system, q is positive; if heat is released, q is negative, leading to the conclusion that q < 0 in this scenario.

Determining the sign of w

The downward movement of the piston indicates a reduction in the system's volume, meaning work was conducted on the system. When work is done on the system, w is considered positive; hence, w > 0 in this case.

Evaluating ΔE sign

According to the first law of thermodynamics, the relationship among ΔE, q, and w is represented as follows:

ΔE = q + w

In this instance, since q is negative and w is positive, the resulting sign of ΔE is determined by the relative magnitudes of q and w. Since we lack sufficient information to gauge these magnitudes, we cannot definitively determine the sign of ΔE based on the given data.

As a result, the correct option among the choices presented is c: q < 0, w > 0, the sign of ΔE cannot be discerned from the information given.

Response:

How can you differentiate a physical change from a chemical change?

Clarification:

Answer:

2.5 g of platinum

Explanation:

A catalyst is a substance added to a reaction to enhance the reaction speed. It does not undergo any change during the reaction, meaning it remains unchanged after the reaction concludes. The role of a catalyst is to provide an alternative pathway for the reaction by reducing the activation energy required. Therefore, a catalyzed reaction occurs more rapidly and requires less energy compared to an uncatalyzed one.

Since catalysts do not get involved in reactions and retain their mass post-reaction, the amount of platinum will stay the same (2.5g). The mass can only alter if a substance participates in the chemical process. Thus, this is the response.