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hammer [34]
3 years ago
10

The density of air at ordinary atmospheric pressure and 25 ∘C is 1.19 g/L. What is the mass, in kilograms, of the air in a room

that measures 12.5 × 19.5 × 6.0 ft?
Chemistry
1 answer:
marshall27 [118]3 years ago
7 0
Given:
The density of air = 1.19 g/L at 25°C and atmospheric pressure,
or
density = 1.19 x 10⁻³ kg/L

Volume of air in the room is
V = 12.5*19.5*6.0 = 1462.5 ft³

Note that
1 ft³ = 28.317 L
Therefore
V = (1462.5 ft³)*(28.317 L/ft³) = 4.1414 x 10 ⁴ L

By definition, mass = density*volume.
Therefore, the mass is
(1.19 x 10⁻³ kg/L)*(4.1414 x 10⁴ L) = 49.283 kg

Answer: 49.3 kg (nearest tenth)
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A boy swings a rubber ball attached to a string over his head in a horizontal, circular path. The piece of string is 1.15 m long
gregori [183]

Answer:

v = 16.49 m/s

Explanation:

Given that,

Length of the string, l = 1.15 m

The ball makes 137 complete turns each minute.

We know that, 1 turn = 6.28 rad

137 turns = 860.79 rad

1 min = 60 s

\omega=\dfrac{860.79\ rad}{60\ s}\\\\=14.34\ rad/s

We need to find the tangential velocity of the ball. It can be given by

v=r\omega\\\\=1.15\times 14.34\\\\v=16.49\ m/s

So, the tangential velocity of the ball is 16.49 m/s.

5 0
3 years ago
when the sum 4.9965 + 2.11 + 3.887 is calculated, to how many decimal places should the answer be reported?
jarptica [38.1K]

Answer:

the correct answer is four decimal places

3 0
3 years ago
What mass of water is produced by the combustion 1.2 x 10^26 molecules of butane ?
podryga [215]

Answer:

17.934 kg of water

Explanation:

If balanced equation is not given; this format can come in handy.

For any alkane of the type : CₙH₂ₙ₊₂ , it's combustion reaction will follow:

2CₙH₂ₙ₊₂ + (3n+1) O₂  →  (2n)CO₂ + 2(n+1) H₂O

For butane:

2C₄H₁₀(g) + 13O₂(g) →  8CO₂(g) + 10H₂O(l)

2 moles of butane gives 10 moles of water.

1 mol of any substance has Avogadro number(N) of molecules in it( 6.022 x 10²³)

Mass of 1 mole of any substance is equal to it's molar mass

So, if 2 x N molecules of butane gives 10 x 18 g of water.

Then  1.2 x 10²⁶ molecules will give:

\frac{1.2 \times 10^{26} \times 180}{2 \times 6.022 \times  10^{23}}

= 17.934 x 10³ g of water

= 17.934 kg of water

5 0
3 years ago
A chemical test has determined the concentration of a solution of an unknown substance to be 2.41 M. a 100.0 mL volume of the so
Oksana_A [137]

Answer : The molar mass of unknown substance is, 39.7 g/mol

Explanation : Given,

Mass of unknown substance = 9.56 g

Volume of solution = 100.0 mL

Molarity = 2.41 M

Molarity : It is defined as the number of moles of solute present in one liter of volume of solution.

Formula used :

\text{Molarity}=\frac{\text{Mass of unknown substance}\times 1000}{\text{Molar mass of unknown substance}\times \text{Volume of solution (in mL)}}

Now put all the given values in this formula, we get:

2.41M=\frac{9.56g\times 1000}{\text{Molar mass of unknown substance}\times 100.0mL}

\text{Molar mass of unknown substance}=39.7g/mol

Therefore, the molar mass of unknown substance is, 39.7 g/mol

5 0
3 years ago
How many moles of liquid water must freeze to remove 100 kJ of heat? (ΔHf = –334 J/<br> g.
Juliette [100K]
First figure out how many grams must freeze and then convert the grams to moles. 
<span>Hf = -334 J/g. Convert this to KJ/g by dividing by 1000. (There are 1000 Joules in a kJ). </span>
<span>Hf = -334 J/g ÷ 1000 J/kj = -0.334 kJ/g </span>
<span>Now, divide 100 kJ by -0.334 kJ/g (see how the units are lining up?) </span>
<span>100 kJ ÷ -0.334 kJ/g = 299 g </span>
<span>Now convert this to moles by dividing by the molecular weight of water (18.0g/mole). </span>
<span>299 ÷ 18.0 = 16.6 moles </span>
5 0
3 years ago
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