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3 years ago

The cube has a mass of 72.9 g. What is its density in g/cm3? What substance is it?

Chemistry

1 answer:

sashaice [31]3 years ago

6 0

If the cube is 3 cm on each side, then it has a volume of 27 cm^3 (3 x 3 x 3). Density is mass divided by volume, so its density is 72.9/27 = 2.7 g/cm^3.

Going by the density, the cube is made of Aluminium - density is a fairly unique quantity

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Which of the below options is not a type of chemical bond?

sashaice [31]

Answer:

magnetic attraction

Explanation:

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3 years ago

The molar mass is determined by measuring the freezing point depression of an aqueous solution. A freezing point of -5.20°C is r

Dima020 [189]

Answer:

The empirical formula is C2H4O3

The molecular formula is C4H8O6

The molar mass is 152 g/mol

Explanation:

The complete question is: An unknown compound contains only carbon, hydrogen, and oxygen. Combustion analysis of the compound gives mass percents of 31.57% C and 5.30% H. The molar mass is determined by measuring the freezing-point depression of an aqueous solution. A freezing point of -5.20°C is recorded for a solution made by dissolving 10.56 g of the compound in 25.0 g water. Determine the empirical formula, molar mass, and molecular formula of the compound. Assume that the compound is a nonelectrolyte.

Step 1: Data given

Mass % of Carbon = 31.57 %

Mass % of H = 5.30 %

Freezing point = -5.20 °C

10.56 grams of the compound dissolved in 25.0 grams of water

Kf water = 1.86 °C kg/mol

Step 2: Calculate moles of Carbon

Suppose 31.57% = 31.57 grams

moles C = mass C / Molar mass C

moles C = 31.57 grams / 12.0 g/mol = 2.63 moles

Step 3: Calculate moles of Hydrogen:

Moles H = 5.30 grams / 1.01 g/mol

moles H = 5.25 moles

Step 4: Calculate moles of Oxygen

Moles O = ( 100 - 31.57 - 5.30) / 16 g/mol

Moles O = 3.95 moles

Step 5: We divide by the smallest number of moles

C: 2.63 / 2.63 = 1 → 2

H: 5.25/2.63 = 2 → 4

O: 3.95/ 2.63 = 1.5 → 3

The empirical formula is C2H4O3

The molar mass of the empirical formula = 76 g/mol

Step 6: Calculate moles solute

Freezing point depression = 5.20 °C = m * 1.86

m = 5.20 / 1.86

m = 2.80 molal = 2.80 moles / kg

2.80 molal * 0.025 kg = 0.07 moles

Step 7: Calculate molar mass

Molar mass = mass / moles

Molar mass = 10.56 grams / 0.07 moles

Molar mass = 151 g/mol

Step 8: Calculate molecular formula

151 / 76 ≈ 2

We have to multiply the empirical formula by 2

2*(C2H4O3) = C4H8O6

The molecular formula is C4H8O6

The molar mass is 152 g/mol

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Answer:

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Explanation:

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Answer:

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A car traveling at a constant speed travels 175 miles in four hours. How many minutes will it take for the car to travel 1000 fe

elena-14-01-66 [18.8K]

It takes 0.26 minutes to travel 1000 feet

Solution:

Given that car traveling at a constant speed travels 175 miles in four hours

Distance = 175 miles

Time taken = 4 hours

Convert the units to feet and minute

Given that,

1 mile = 5280 feet

175 miles = 5280 x 175 feet = 918720 feet

Also we know that,

1 hour = 60 minutes

4 hours = 60 x 4 minutes = 240 minutes

Thus, we got,

Distance = 918720 feet

Time taken = 240 minutes

Find the speed of car

Speed is given by formula:

$speed = \frac{distance}{time}$

$speed = \frac{918720}{240} = 3828$

Thus speed of car is 3828 feet per minute

How many minutes will it take for the car to travel 1000 feet?

Let "x" be the minutes needed for 1000 feet

speed of car is 3828 feet per minute

1 minute = 3828 feet

x minute = 1000 feet

This forms a proportion. We can solve by cross multiplying

$x \times 3828 = 1000 \times 1\\\\x = \frac{1000}{3828}\\\\x = 0.26$

Thus it takes 0.26 minutes to travel 1000 feet

7 0

3 years ago