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2 years ago

Which is correct if 15,390,000 is rounded to two significant figures?

Chemistry

1 answer:

BARSIC [14]2 years ago

7 0

Answer:

Explanation:

Remark

This is one of those questions that you need the choices. You can't tell what you should enter. For example, in scientific notation, you would get 1.5*10^7.

Or you could keep it as an integer and round to two places 150,000,000,

I would pick scientific notation if you know how to use it. Otherwise use the interger format.

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A cubic box with sides of 20.0 cm contains 2.00 × 1023 molecules of helium with a root-mean-square speed (thermal speed) of 200

Anarel [89]

Answer:

1.133 kPa is the average pressure exerted by the molecules on the walls of the container.

Explanation:

Side of the cubic box = s = 20.0 cm

Volume of the box ,V= $s^3$

$V=(20.0 cm)^3=8000 cm^3=8\times 10^{-3} m^3$

Root mean square speed of the of helium molecule : 200m/s

The formula used for root mean square speed is:

$\mu=\sqrt{\frac{3kN_AT}{M}}$

where,

= root mean square speed

k = Boltzmann’s constant = $1.38\times 10^{-23}J/K$

T = temperature = 370 K

M = mass helium = $3.40\times 10^{-27}kg/mole$

$N_A$ = Avogadro’s number = $6.022\times 10^{23}mol^{-1}$

$T=\frac{\mu _{rms}^2\times M}{3kN_A}$

Moles of helium gas = n

Number of helium molecules = N = $2.00\times 10^{23}$

N = $N_A\times n$

Ideal gas equation:

PV = nRT

Substitution of values of T and n from above :

$PV=\frac{N}{N_A}\times R\times \frac{\mu _{rms}^2\times M}{3kN_A}$

$PV=\frac{N\times R\times \mu ^2\times M}{3k\times (N_A)^2}$

$R=k\times N_A$

$PV=\frac{N\times \mu ^2\times M}{3}$

$P=\frac{2.00\times 10^{23}\times (200 m/s)^2\times 3.40\times 10^{-27} kg/mol}{3\times 8\times 10^{-3} m^3}$

$P=1133.33 Pa =1.133 kPa$

(1 Pa = 0.001 kPa)

1.133 kPa is the average pressure exerted by the molecules on the walls of the container.

3 0

3 years ago

What is the mass percent concentration of a solution containing 29.0 g NaCl and 115.0 mL of water? Assume a density of 1.00 g/mL

marin [14]

Answer:

Mass percent concentration: 25,2% m/m

Explanation:

The percentage mass by mass indicates the grams of solute in 100 grams of solution. We convert the ml of water into g from the density formula:

δ= m/v m=δx v= 1 g/ml x 115 ml= 115 g

115g solution-----29 g NaCl

100g solution----x=(100g solutionx29 g NaCl)/115g solution

x=25,2173913 g NaCl

5 0

3 years ago

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melamori03 [73]

Answer:

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Explanation:

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Answer:

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nadezda [96]

Answer:

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4 years ago