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3 years ago

10

sketch and label a helium-4 atom and helium-5 atom to include the protons, neutrons, and electrons. how are they alike and how a

re they different?

2 answers:

Doss [256]3 years ago

8 0

Answer:

Protons-2 for both

neutrons-2 for helium-4 and neutrons-3 for helium-5

electrons-1 for both

Explanation:

draw a ring and put protons and neutrons in the middle and the electrons on the ring

Naily [24]3 years ago

4 0

Answer:

U cant sketch on here mate

Explanation:

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4 moles of hydrogen react with 5 moles of oxygen to form water, identify the excess reagent?

Fynjy0 [20]

Answer:

Excess Reagent = oxygen

Explanation:

Limiting reagent: The substance that is totally consumed when the reaction is completed.

Excess reagent: The substance left after the limiting reagent is consumed completely

The balanced chemical equation for formation of water is as follow:

$2H_{2}+O_{2}\rightarrow 2H_{2}O$

This means when 2 moles of hydrogen reacts with 1 mole of oxygen, 2 moles of water is produced.

Hence the ratio in which hydrogen and oxygen gas reacts is 2:1

Now if 2 mole hydrogen require 1 mole of oxygen ,then 4 mole hydrogen need 2 mole of oxygen.

$H_{2}:O_{2}=2:1$

or

$H_{2}:O_{2}=4:2$

Here 5 mole of oxygen is reacting but only 2 mole is required .

Oxygen is in excess.

5 0

3 years ago

How do you do part B?

galina1969 [7]

I cannot see the whole equation.Therefore I shall not answer

7 0

3 years ago

The radius of a hydrogen atom is 37 pm and its mass is 1.67 × 10-24 g. What is the density of the atom in grams per cubic centim

RoseWind [281]

Answer:

V = 4/3 * 3.1416 * (37x10-10)3

V = 2.12x10-25 cm3

d = m/V

d = 1.67x10-24 / 2.12x10-25 = 7.87 g/cm3

The difference in temperature, let's convert F to ºC:

ºC = -80-32/1.8 = -62.22 ºC

dT = -92.6 + 62.2 = -30.4 ºC

4 0

4 years ago

Read 2 more answers

How many formula units make up 24.2 g of magnesium chloride (MgCl2)?<br><br> Help!!

NNADVOKAT [17]

Answer:

Approximately $1.53 \times 10^{23}$ formula units ( $0.254\; \rm mol$ ).

Explanation:

Refer to a modern periodic table for the relative atomic mass of magnesium ( $\rm Mg$ ) and chlorine ( $\rm Cl$ ):

$\rm Mg$ : $24.305$ .
$\rm Cl$ : $35.45$ .

In other words, the mass of $1\; \rm mol$ of $\rm Mg$ atoms would be (approximately) $24.305\; \rm g$ .

Likewise, the mass of $1\; \rm mol$ of $\rm Cl$ atoms would be approximately $35.45\; \rm g$ .

One formula unit of the ionic compound $\rm MgCl_{2}$ includes exactly as many atoms as there are in the given formula. The formula mass of a compound is the mass of $1\; \rm mol$ of the formula units of this compound.

The formula $\rm MgCl_{2}$ includes one $\rm Mg$ atom and two $\rm Cl$ atoms.

Hence, every formula unit of $\rm MgCl_{2} \!$ would include the same number of atoms: one $\rm Mg\!$ atom and two $\rm Cl\!$ atoms. There would be $1\; \rm mol$ of $\rm Mg$ atoms and $2\; \rm mol$ of $\rm Cl$ atoms in $1\; \rm mol\!$ of $\rm MgCl_{2}$ formula units.

Thus, the mass of $1\; \rm mol\!$ of $\rm MgCl_{2}$ formula units would be equal to the mass of $1\; \rm mol$ of $\rm Mg$ atoms plus the mass of $2\; \rm mol$ of $\rm Cl$ atoms. (The mass of $1\; \rm mol\!\!$ of each atom could be found from the relative atomic mass of each element.)

$\begin{aligned}& M({\rm MgCl_{2}}) \\ =\; & 24.305\; {\rm g \cdot mol^{-1}} + 2\times {\rm 35.45 \; \rm g \cdot mol^{-1}} \\ =\; & 95.205\; \rm g \cdot mol^{-1}\end{aligned}$ .

In other words, the formula mass of $\rm MgCl_{2}$ is $95.205\; \rm g \cdot mol^{-1}$ .

Therefore, the number of formula units in $m = 24.2\; \rm g$ of $\rm MgCl_{2}$ would be:

$\begin{aligned}n &= \frac{m({\rm MgCl_{2}})}{M({\rm MgCl_{2}})} \\ &= \frac{24.2\; \rm g}{95.205\; \rm g\cdot mol^{-1}} \\ & \approx 0.254\; \rm mol\end{aligned}$ .

Multiple $n$ by Avogadro's Number $N_{A} \approx 6.022 \times 10^{23}\; \rm mol^{-1}$ to estimate the number of formula units in $0.254\; \rm mol$ :

$\begin{aligned}N &= n \cdot N_{A} \\ &\approx 0.254\; \rm mol \times 6.022 \times 10^{23}\; \rm mol^{-1} \\ &\approx 1.53\times 10^{23}\end{aligned}$ .

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3 years ago

Which property of waves is the distance between one point on a wave and that same point on the wave next to it?

mr Goodwill [35]

The answer is B, wavelength

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3 years ago

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