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ValentinkaMS [17]
2 years ago
14

How many moles are in 987 grams of : Ra(OH)2

Chemistry
2 answers:
sergejj [24]2 years ago
8 0
Your answer is 3.80 moles
likoan [24]2 years ago
6 0
Here are the molar masses of these atoms:

Ra = 226 g/mol

H = 1.008 g/mol * 2 (there are two hydrogen atoms in radium hydroxide)

O = 15.999 g/mol * 2

The molar mass of radium hydroxide is therefore 260.014 g/mol.

Divide this number by 987 grams to cancel the units in order to obtain the number moles.

260.014 g/mol / 987 g = 0.263 mol
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Zinc is to be electroplated onto both sides of an iron sheet that is 20 cm2 as a galvanized sacrificial anode. It is desired to
Alexandra [31]

Answer:

The time required for the coating is 105 s

Explanation:

Zinc undergoes reduction reaction and absorbs two (2) electron ions.

The expression for the mass change at electrode (m_{ch}) is given as :

\frac{m_{ch}}{M} ZF = It

where;

M = molar mass

Z = ions charge at electrodes

F = Faraday's constant

I = current

A = area

t = time

also; (m_{ch}) = (Ad) \rho ; replacing that into above equation; we have:

\frac{(Ad) \rho}{M} ZF = It  ---- equation (1)

where;

A = area

d = thickness

\rho = density

From the above equation (1); The time required for coating can be calculated as;

[ \frac{20 cm^2 *0.0025 cm*7.13g/cm^3}{65.38g/mol}*2 \frac{moles\ of \ electrons}{mole \ of \ Zn} * 9.65*10^4 \frac{C}{mole \ of \ electrons }  ] = (20 A) t

t = \frac{2100}{20}

= 105 s

8 0
2 years ago
Which of the following correctly describes a compound? (4 points)
wariber [46]

Explanation:

The atoms are chemically bonded together, and they retain their individual physical and chemical properties.

8 0
2 years ago
Why does 5060 have three significant figures?
Morgarella [4.7K]
<h2>5060 have three significant figures : Explanation given below </h2>

Explanation:

Significant figures

The significant figures (also known as the significant digits and decimal places) of a number are digits that possess certain  meaning .

It  includes all digits except: zeros

Rules to find significant figures

1.All non-zero digits are considered significant. For example, 23  has two significant figures.

2.Zeros in between two non-zero digits are significant: like in 202.1201  has seven significant figures.

3.Zeros to the left of the significant figures are not significant. For example, .000021 has two significant figures, zeros have no value .

4.Zeros to the right of the significant figures are significant.

That is the reason in number 5060 , it has 3 significant figures .

3 0
2 years ago
How many hydrogen bonds can CH2O make to water
VladimirAG [237]
Hydrogen bonds are not like covalent bonds. They are nowhere near as strong and you can't think of them in terms of a definite number like a valence. Polar molecules interact with each other and hydrogen bonds are an example of this where the interaction is especially strong. In your example you could represent it like this: 

<span>H2C=O---------H-OH </span>

<span>But you should remember that the H2O molecule will be exchanging constantly with others in the solvation shell of the formaldehyde molecule and these in turn will be exchanging with other H2O molecules in the bulk solution. </span>

<span>Formaldehyde in aqueous solution is in equilibrium with its hydrate. </span>

<span>H2C=O + H2O <-----------------> H2C(OH)2</span>
5 0
2 years ago
You have 49.8 g of O2 gas in a container with twice the volume as one with CO2 gas. The pressure and temperature of both contain
IrinaVladis [17]

Answer:

34.2 g is the mass of carbon dioxide gas one have in the container.

Explanation:

Moles of O_2:-

Mass = 49.8 g

Molar mass of oxygen gas = 32 g/mol

The formula for the calculation of moles is shown below:

moles = \frac{Mass\ taken}{Molar\ mass}

Thus,

Moles= \frac{49.8\ g}{32\ g/mol}

Moles_{O_2}= 1.55625\ mol

Since pressure and volume are constant, we can use the Avogadro's law  as:-

\frac {V_1}{n_1}=\frac {V_2}{n_2}

Given ,  

V₂ is twice the volume of V₁

V₂ = 2V₁

n₁ = ?

n₂ = 1.55625 mol

Using above equation as:

\frac {V_1}{n_1}=\frac {V_2}{n_2}

\frac {V_1}{n_1}=\frac {2\times V_1}{1.55625}

n₁ = 0.778125 moles

Moles of carbon dioxide = 0.778125 moles

Molar mass of CO_2 = 44.0 g/mol

Mass of CO_2 = Moles × Molar mass = 0.778125 × 44.0 g = 34.2 g

<u>34.2 g is the mass of carbon dioxide gas one have in the container.</u>

5 0
2 years ago
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