How many moles of nitrogen gas are there in 6.8 liters at room temperature and pressure (293 K and 100 kPa)?

Answer: The process of heating a crucible to eliminate moisture from a hydrate.

Explanation:

The available choices are:

a. Heating a solvent to aid in the dissolution of a solute.

b. Heating a solid in isolation to remove moisture.

c. Bringing water to a boil for use in a water bath.

d. Heating a crucible to eliminate moisture from a hydrate.

Possible actions that can be done on a hot plate include:

a. Heating a solvent to assist a solute in dissolving.

b. Heating a solid in isolation to dry it.

c. Heating water to boiling for a water bath.

However, it's important to note that using a hot plate for heating a crucible to remove water from a hydrate is not advisable. Silica or ceramic materials are not meant to be heated on a hot plate.

Consequently, the correct procedure is heating a crucible to remove water from a hydrate.

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.

Answer:

Nylon and Spandex (Lycra).

Explanation:

These materials are designed to fit the body, with nylon drying more quickly than other types of fabrics, and Spandex being commonly found in swimming and sports apparel due to its elastic qualities. Both fabrics also wick moisture away and dry rapidly.

With high capacity and enhanced flexibility, nylon and Spandex provide a snug fit to the body and can retain their shape during various activities, making them ideal for swimming.

This explains why these materials are suitable based on the situation given.

Answer:

The integer value of x in the hydrate is 10.

Explanation:

Molar concentration of the solution = 0.0366 M

Volume of the solution = 5.00 L

Moles of hydrated sodium carbonate = n

Weight of hydrated sodium carbonate = n = 52.2 g

Molar mass of hydrated sodium carbonate = 106 g/mol + x * 18 g/mol

By solving for x, we arrive at:

x = 9.95, approximating to 10

The integer x in the hydrate equals 10.

Answer:

thickness is 0.29 cm

Explanation:

To create a fake iron ball out of gold, we must ensure that its mass matches that of the iron ball. Therefore, we first find the volume of the iron ball using the provided diameter, applying the formula of 4/3 pi r^3.

Given the diameter d = 6 cm; thus, the radius r = 3 cm (d/2).

We calculate the volume of the iron ball: 4/3 * 3.14 * 3^3 = 113.04 cm^3.

The corresponding mass of the iron ball is the volume multiplied by its density: 113.04 * 5.15 g/cm^3 = 582.156 g.

This value represents the mass for the gold ball; now we determine the volume of the gold ball using its density.

Volume of gold ball = mass of gold ball/density of gold = 582.156 g/19.3 g/cm^3 = 30.1635 cm^3.

So this volume must correspond to a hollow sphere with an outer radius R = 3 cm and an unknown inner radius r.

Volume of the hollow ball can be represented as: 4/3 pi [R^3 - r^3].

Thus, 30.1635 cm^3 = 4/3 pi [3^3 - r^3].

30.1635 * 3/(4 * 3.14) = 27 - r^3.

Simplifying gives 7.2046 = 27 - r^3, resulting in r^3 = 19.7954.

Therefore, r = 2.7051 cm.

This indicates the thickness is the outer radius minus the inner radius: 3 - 2.7051 = 0.2949 cm.

Rounding to two significant figures yields

the thickness = 0.29 cm.