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3 years ago

How many moles of MgCl2 are there in 305 g of the compound? Answer and units

1 answer:

8 0

Wrong subject. Expect that to be in chemistry.

Here it is:

One mole of a compound/element contains the weight in grams equal to the sum of the molecular mass.
For MgCL2,
Mg=24.30
Cl=35.45
so the molecular mass = 24.30+2*35.45=24.30+70.9=95.20 (approximately).
=>
One mole of MgCl2 weighs 95.20 g.

305 g of MgCl2 = 305/95.20 = 3.20 moles, to 3 significant figures

Edit: improved accuracy of atomic masses.

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The irreversible thermite reaction (Fe2O3 + 2 Al --> 2 Fe + Al2O3) is highly exothermic, changing the temperature by over 100

likoan [24]

Answer:

the water will boil and change into a gas

Explanation:

This is because it is exothermic and releases the energy into the surroundings and the fact that water boils at 100 degrees Celsius

6 0

3 years ago

Per person, the energy consumption in the United States is about 3.3 × 10^8 Btu/yr. This is equivalent to a power of:________. A

zhuklara [117]

Answer:

$3.3\times 10^8\ btu/yr=11\ kW$

Explanation:

Btu of British thermal unit is a unit of heat. The relation between btu/year and watts is given by :

$1\ btu/yr=3.343\times 10^{-5}\ W\\\\3.3\times 10^8\ btu/yr=3.343\times 10^{-5}\times 3.3\times 10^8\ W\\\\3.3\times 10^8\ btu/yr=11031.9\ W\\\\3.3\times 10^8\ btu/yr=11\ kW$

So, $3.3\times 10^8\ btu/yr$ is equal to 11 kW. Hence, the correct option is (d).

4 0

3 years ago

A 50g ball is released from rest 1.0 above the bottom of thetrack

ludmilkaskok [199]

Answer:

The maximum height of the ball is 2 m.

Explanation:

Given that,

Mass of ball = 50 g

Height = 1.0 m

Angle = 30°

The equation is

$y=\dfrac{1}{4}x^2$

We need to calculate the velocity

Using conservation of energy

$\Delta U_{i}+\Delta K_{i}=\Delta K_{f}+\Delta U_{f}$

Here, ball at rest so initial kinetic energy is zero and at the bottom the potential energy is zero

$\Delta U_{i}=\Delta K_{f}$

Put the value into the formula

$mgh=\dfrac{1}{2}mv^2$

Put the value into the formula

$50\times10^{-3}\times9.8\times1.0=\dfrac{1}{2}\times50\times10^{-3}\times v^2$

$v^2=\dfrac{2\times50\times10^{-3}\times9.8\times1.0}{50\times10^{-3}}$

$v=\sqrt{19.6}$

$v=4.42\ m/s$

We need to calculate the maximum height of the ball

Using again conservation of energy

$\dfrac{1}{2}mv^2=mgh$

Here, h = y highest point

Put the value into the formula

$\dfrac{1}{2}\times50\times10^{-3}\times(4.42)^2=50\times10^{-3}\times9.8\times h$

$y=\dfrac{0.5\times(4.42)^2}{9.8}$

$y=0.996\ m$

Put the value of y in the given equation

$y=\dfrac{1}{4}x^2$

$x^2=4\times0.996$

$x=\sqrt{4\times0.996}$

$x=1.99\ m\ \approx 2 m$

Hence, The maximum height of the ball is 2 m.

4 0

3 years ago

A satellite of Mars, called Phobos, has an orbital radius of 9.4 ✕ 106 m and a period of 2.8 ✕ 104 s. Assuming the orbit is circ

FromTheMoon [43]

Answer:

$6.27*10^{23}kg$

Explanation:

assume

M= mass of Mars

m=mass of phobos

r=orbital radius

T=period

we can apply F=ma to this orbital motion (considering the cricular motion laws)

where,

$F=\frac{GMm}{r^{2} }$ and a=rω^2

where ω= $\frac{2\pi }{T}$ and G is the universal gravitational constant.

G = 6.67 x 10-11 N m2 / kg2

$F=ma\\\frac{GMm}{r^{2} }=mr(\frac{2\pi }{T} )^{2}\\ M=\frac{r^{3}}{G} (\frac{2\pi }{T} )^{2}\\M=\frac{(9.4*10x^{6} )^{3}*(2\pi )^{2} }{(2.8*10^{4}) ^{2} *6.67*10^{-11} } \\M=6.27*10^{23}kg$

6 0

3 years ago

Why is a magnet strongest at its poles ??

Softa [21]

Answer:

magnetic fields is stronger at the pulls because opposites attract which is why the pull is stronger.

this was written by me.

Explanation:

8 0

3 years ago