B. Everyone knows that water is supposed to boil at 100° C. Why did your water sample
boil at a different temperature?
C. While heating two different samples of water at sealevel, one boils at 102o C and one
boils at 99.2o C. Calculate the percent error for each from the theoretical 100.0o C.
D. An unknown rectangular substance measures 3.6 cm high, 4.21 cm long, and 1.17
cm wide. If the mass is 21.3g, what is this substance’s density?
E. A sample of gold (Au) has a mass of 26.15 g. Given that the theoretical density is
19.30 g/mL, what is the volume of your gold sample?
F. You are given a small piece of gold to analyze. Using the Archimedes Principle you
find that the volume is 0.40 cm3; and its mass is 6.0 g. What conclusions can you
reach from your simple density analysis?
G. How would one prepare 10 ml of a 0.25 M HCl solution if 1 M HCl was available?
How much 1 M HCl is needed? How much distilled water is used?
To help you get a feel for metric measurements, you need to know the relative magnitude of
a few basic measurements. For example: 1 mm = thickness of a dime, a penny weighs 2 ½
grams, and 20°C = normal room temperature.
H. Determine the following:
1. What is your mass or the mass of a friend, pet, or some large object in
kilograms (kg)? Don’t forget to identify the mass you are listing.
2. What weighs approximately 1 g?
3. What is approximately 1 cm long, wide or thick?
4. What weighs about 100 g?
5. What weighs about 1000 g
I suggest you post these question one per post AND explain exactly what you don't understand about each OR tell us how you would approach the problem.
An unknown rectangular substance measures 3.6 cm high, 4.21 cm long, and 1.17 cm wide. If the mass is 21.3g, what is this substance’s density?
B. There could be several reasons why the water sample boiled at a different temperature than the expected 100°C. Some possible reasons could be variations in atmospheric pressure, impurities in the water, or the presence of dissolved substances that raise or lower the boiling point.
C. To calculate the percent error for each of the boiling points, you can use the formula:
Percent error = ((experimental value - theoretical value) / theoretical value) * 100
For the first sample boiling at 102°C:
Percent error = ((102 - 100) / 100) * 100 = 2%
For the second sample boiling at 99.2°C:
Percent error = ((99.2 - 100) / 100) * 100 = -0.8%
D. To calculate the density of the rectangular substance, you can use the formula:
Density = mass / volume
Given:
Height (h) = 3.6 cm
Length (l) = 4.21 cm
Width (w) = 1.17 cm
Mass (m) = 21.3 g
Volume (V) = h * l * w = 3.6 cm * 4.21 cm * 1.17 cm = 18.41 cm^3
Density = mass / volume = 21.3 g / 18.41 cm^3 ≈ 1.157 g/cm^3
E. To calculate the volume of the gold sample, you can use the formula:
Volume = mass / density
Given:
Mass (m) = 26.15 g
Density (d) = 19.30 g/mL
Volume = mass / density = 26.15 g / 19.30 g/mL ≈ 1.35 mL
F. From the simple density analysis, you can conclude that the density of the gold sample is 15 g/cm^3 (calculated as mass/volume = 6.0 g / 0.40 cm^3 = 15 g/cm^3). This density value can be compared to the known density of gold (which is approximately 19.30 g/mL) to determine if the sample is genuine gold or a different material with a similar density.
G. To prepare 10 mL of a 0.25 M HCl solution using 1 M HCl, you can use the formula:
M1V1 = M2V2
Given:
M1 = 1 M (concentration of 1 M HCl)
V1 = ?
M2 = 0.25 M (desired concentration of the solution)
V2 = 10 mL (desired volume of the solution)
Rearranging the formula:
V1 = (M2 * V2) / M1 = (0.25 M * 10 mL) / 1 M = 2.5 mL of 1 M HCl
To calculate the amount of distilled water used, subtract the volume of 1 M HCl from the total desired volume:
Distilled water volume = 10 mL - 2.5 mL = 7.5 mL
H.
1. The mass of a friend, pet, or some large object in kilograms would depend on the specific object and would need to be measured.
2. Something that weighs approximately 1 gram is a small paperclip or a dollar bill.
3. Something that is approximately 1 cm long, wide, or thick is a standard LEGO brick.
4. Something that weighs about 100 grams is a small apple or a lightbulb.
5. Something that weighs about 1000 grams is a large bottle of soda or a small laptop.
B. The boiling point of water can vary due to factors such as altitude, impurities in the water, and the presence of dissolved substances. To determine the boiling point of a specific water sample, you can use a thermometer and heat the water until it reaches a rolling boil. Make sure to adjust for any variations in atmospheric pressure.
C. To calculate the percent error for each sample of water boiling at different temperatures from the theoretical boiling point of 100.0°C, you can use the formula:
Percent Error = [(Measured Value - Theoretical Value) / Theoretical Value] x 100
For example, for the first sample boiling at 102.0°C:
Percent Error = [(102.0 - 100.0) / 100.0] x 100 = 2.0%
And for the second sample boiling at 99.2°C:
Percent Error = [(99.2 - 100.0) / 100.0] x 100 = -0.8%
D. Density is calculated by dividing the mass of a substance by its volume. In this case, to find the density of the unknown rectangular substance, you can use the formula:
Density = Mass / Volume
Density = 21.3g / (3.6cm x 4.21cm x 1.17cm) = density in g/cm³
E. To find the volume of the gold sample, you can use the formula:
Volume = Mass / Density
Volume = 26.15g / 19.30g/mL = volume in mL
F. From the given data, you can calculate the density of the gold sample using the formula:
Density = Mass / Volume
Density = 6.0g / 0.40cm³ = density in g/cm³
By comparing the calculated density with the known density of gold (19.30 g/mL), you can conclude whether the sample is consistent with gold or not.
G. To prepare a 10 mL of a 0.25 M HCl solution using 1 M HCl, you can use the formula:
C1V1 = C2V2
1 M x V1 = 0.25 M x 10 mL
V1 = (0.25 M x 10 mL) / 1 M = 2.5 mL of 1 M HCl needed
To determine the amount of distilled water needed:
Distilled Water = Total Volume - HCl Solution Volume
Distilled Water = 10 mL - 2.5 mL = 7.5 mL of distilled water needed.
H.
1. The mass of a person might be around 70 kilograms (kg).
2. A paperclip weighs approximately 1 gram (g).
3. The width of a standard US dime is approximately 1 centimeter (cm).
4. A medium-sized apple weighs about 100 grams (g).
5. A liter of water weighs about 1000 grams (g) or 1 kilogram (kg).