A balloon filled with helium occupies 20.0 l at 1.50 atm and 25.0◦

1 answer:

5 0

At stp (standard temperature and pressure), the temperature is T=0 C=273 K and the pressure is p=1.00 atm. So we can use the ideal gas law to find the number of moles of helium:
$pV=nRT$
where p is the pressure (1.00 atm), V the volume (20.0 L), n the number of moles, T the temperature (273 K) and $R=0.082 atm L K^{-1} mol^{-1}$ the gas constant. Using the numbers and re-arranging the formula, we can calculate n:
$n= \frac{pV}{RT}= \frac{(1.00atm)(20.0L)}{(0.082 LatmK^{-1}mol^{-1})(273 K)}=0.89 mol$

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2 years ago

An object has a position given by the radius vector r = [2.0 m + (3.00 m/s)t](i)+ [3.0 m - (2.00 m/s^2)t^2](j). Here (i) and (j)

jenyasd209 [6]

Answer:

The speed of the object is ( $3i - 4.00tj$ )m/s

The magnitude of the acceleration is 4.00m/s²

Explanation:

Given - position vector;

r = (2.0 + 3.00t)i + (3.0 - 2.00t²)j -------------------(i)

To get the speed vector ( $v$ ), take the first derivative of equation (i) with respect to time t as follows;

$v$ = $\frac{dr}{dt}$

$v$ = $\frac{d[(2.0 + 3.00t)i + (3.0 - 2.00t^2)j] }{dt}$

$v$ = $3i - 4.00tj$ ------------------------(ii)

To get the acceleration vector ( $a$ ), take the first derivative of the speed vector in equation(ii) as follows;

$a = \frac{dv}{dt}$

$a = \frac{d(3i - 4.00tj)}{dt}$

$a = -4.00$ j

The magnitude of the acceleration |a| is therefore given by

|a| = |-4.00|

|a| = 4.00 m/s²

In conclusion;

the speed of the object is ( $3i - 4.00tj$ )m/s

the magnitude of the acceleration is 4.00m/s²

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2 years ago

A large piece of jewelry has a mass of 132.6 g. a graduated cylinder initially contains 48.6 ml water. when the jewelry is subme

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The density of the substance is 10.5 g/cm³.

The jewelry is made out of Silver.

Density ρ is defined as the ratio of mass m of the substance to its volume V. The cylinder contains a volume V₁ of water and when the jewelry is immersed in it, the total volume of water and the jewelry is found to be V₂.

The volume V of the jewelry is given by,

$V=V_2 -V_1$