So I saw this question: If 28.0 grams of Pb(NO3)2 react with 18.0 grams of NaI, what mass of PbI2 can be produced? Pb(NO3)2 + NaI → PbI2 + NaNO3

I saw an answer that question but I need one part explained. The answer balanced the equation, but I do not know how they did that or why. They added a 2 to both sides and I do not know where it came from or why it made it balanced.

Answers

Answer 1

mass of PbI₂ = 27.6606 g

Further explanation

Given

Pb(NO₃)₂ + NaI → PbI₂ + NaNO₃

28.0 grams of Pb(NO₃)₂ react with 18.0 grams of NaI

Required

mass of PbI₂

Solution

Balanced equation

Pb(NO₃)₂ + 2NaI → PbI₂ + 2NaNO₃

The principle of a balanced reaction is the number of atoms in the reactants = the number of atoms in the product

mol Pb(NO₃)₂ :

= 28 : 331,2 g/mol

= 0.0845

mol NaI :

= 18 : 149,89 g/mol

= 0.12

Limiting reactant : mol : coefficient

Pb(NO₃)₂ : 0.0845 : 1 = 0.0845

NaI : 0.12 : 2 = 0.06

NaI limiting reactant (smaller ratio)

mol PbI₂ based on NaI

= 1/2 x 0.12 = 0.06

Mass PbI₂ :

= 0.06 x 461,01 g/mol

= 27.6606 g


Related Questions

If you have 3.5 L of He to blow up balloons... at STP...

a) How many moles of He do you have?

b) How many grams of He do you have?

Answers

Answer:

B

Explanation:

show work!!
A sample is 54.7g CaCl2 and 53.64 g H20. How
many water molecules are associated with this
hydrate?

Answers

The molecular formula of hydrate : CaCl₂.6 H₂O

So there are 6 molecules of H₂O

Further explanation

Given

54.7g CaCl₂ and 53.64 g H₂O

Required

The number of molecules H₂O

Solution

mol CaCl₂ :

= mass : MW

= 54.7 : 111 g/mol

= 0.493

mol H₂O :

= 53.64 : 18 g/mol

= 2.98

mol ratio H₂O : CaCl₂ :

= 2.98/0.493 : 0.493/0.493

= 6 : 1

helpppp nowww plssss nowww!!

Answers

Earth’s rotation on its axis makes the moon appear to rise and set

What is the mass of 1.75 moles of Ca(H2C302)2?

Answers

Explanation:

first we have to find molar mass of ca(H2c3o2)2

40+(1*2)2+(12*3)2+(16*2)2

40+4+72+64=180g/mole

m=n*Mm

m=1.75mole*180g/mole

m=315g

A state of matter where the particles that make up a substance start to break apart

Answers

Answer:

Liquid

Explanation:

Why are the non-living things important to an ecosystem?

Answers

Answer:

well just like grass that helps animals eat rocks may give an animal a home

It’s just like grass it helps animals eat rocks May do a home for them to

It is desirable to remove calcium ion from hard water to prevent the formation of precipitates known as boiler scale that reduce heating efficiency. The calcium ion is reacted with sodium phosphate to form solid calcium phosphate, which is easier to remove than boiler scale. What volume (in liters) of 0.478 M sodium phosphate is needed to react completely with 0.225 liter of 0.279 M calcium chloride

Answers

Answer:

0.0876L of 0.478M Na₃PO₄ are needed

Explanation:

The reaction of calcium chloride, CaCl₂, with sodium phosphate, Na₃PO₄ is:

3CaCl₂ + 2Na₃PO₄ → Ca₃(PO₄)₂ + 6NaCl

Where 3 moles of calcium chloride react with 2 moles of sodium phosphate to produce 1 mole of calcium phosphate.

To solve this question we need to find moles of CaCl₂ added. Using the reaction we can find the moles of Na₃PO₄ that are needed to react completely and the volume using its concentration:

Moles CaCl₂:

0.225L * (0.279mol / L) = 0.0628moles of CaCl₂

Moles Na₃PO₄:

0.0628moles of CaCl₂ * (2mol Na₃PO₄ / 3 mol CaCl₂) =

0.0419moles of Na₃PO₄

Volume 0.478M Na₃PO₄:

0.0419moles of Na₃PO₄ * (1L / 0.478mol) =

0.0876L of 0.478M Na₃PO₄ are needed

When she introduced CO(g) and Cl2(g) into a 1.00 L evacuated container, so that the initial partial pressure of CO was 1.86 atm and the initial partial pressure of Cl2 was 1.27 atm, she found that the equilibrium partial pressure of COCl2 was 0.823 atm. Calculate the equilibrium constant, Kp, she obtained for this reaction.

Answers

Answer:

Kp is 0.00177

Explanation:

We state the equilibrium:

CO(g) + Cl₂(g)  ⇆  COCl₂(g)

Initially we have these partial pressures

1.86 atm for CO and 1.27 for chlorine.

During the reaction, x pressure has been converted. As we have 0.823 atm as final pressure in the equilibrium for COCl₂, pressure at equilibrium for CO and chlorine will be:

1.86 - x for CO and 1.27 - x for Cl₂.

And x is the pressure generated for the product, because initially we don't have anything from it. So pressure in equilibrium for the reactants will be:

1.86 - 0.823 = 1.037 atm for CO

1.27 - 0.823 = 0.447 atm for Cl₂

Let's make, expression for Kp:

Partial pressure in eq. for  COCl₂ / P. pressure in eq. for CO . P pressure in eq. for Cl₂

Kp = 0.823 / (1.037 .  0.447) → 0.00177

In the reaction 2 HgO --> 2 Hg + O2
how many moles of O2 are produced when 5 moles of HgO are decomposed?

Answers

Answer:

2.5 moles of oxygen are produced.

Explanation:

Given data:

Number of moles of O₂ produced = ?

Number of moles of HgO decomposed = 5 mol

Solution:

Chemical equation:

2HgO      →     2Hg + O₂

now we will compare the moles of HgO and O₂.

           HgO         :          O₂

            2              :          1

            5              :         1/2×5 = 2.5

Thus, from 5 moles of HgO 2.5 moles of oxygen are produced.

How many mols in 2.25x10^25 atoms of Zinc

Answers

Answer:

37.4 mol.

Explanation:

Hello!

In this case, since the Avogadro's number help us to realize that one mole of any substance contains 6.022x10²³ formula units, in this case atoms of zinc, the following dimensional analysis provides the correct answer:

[tex]=2.25x10^{25} atoms*\frac{1mol}{6.022x10^{23}atoms}\\\\= 37.4mol[/tex]

Best regards!

What is the oxidation number of calcium

Answers

Answer:

0 for the elemental form, +2 in its compounds.

A 5.5 gg sample of a substance contains only carbon and oxygen. Carbon makes up 35%% of the mass of the substance. The rest is made of oxygen. You are asked to determine the mass of oxygen in the sample. Which of the following expressions demonstrates a mathematical procedure to solve this problem using the proper order of operations?

a. ((100 - 35)/100) times 5.5 grams =
b. 100 - 35/100 times 5.5 grams =
c. 100 - (35/100) times 5.5 grams=

Answers

Answer:

a. ((100 - 35)/100) times 5.5 grams = 3.575 g

Explanation:

Given that:

The sample of carbon and oxygen = 5.5g

where carbon makes 35% of the mass of the substances.

It implies that oxygen will make: (100 - 35)% = 65%

Suppose y be the mass of the oxygen;

Then:

[tex]y = \dfrac{(100-35)}{100} \times 5.5 \ g[/tex]

[tex]y = \dfrac{(65)} {100} \times 5.5 \ g[/tex]

[tex]y = 3.575 \ g[/tex]

The mass of carbon [tex]= \dfrac{35}{100} \times 5.5 \ g[/tex]

= 1.925 g

Where and in what features is water found on Earth?

Answers

Answer:  On Earth, liquid water exists on the surface in the form of oceans, lakes and rivers. It also exists below ground as groundwater, in wells and aquifers. Water vapor is most visible as clouds and fog. The frozen part of Earth's hydrosphere is made of ice: glaciers, ice caps and icebergs.

what is the difference between test tube and boiling tube​

Answers

Test tubes heat small amounts of liquids while boiling tube boils liquids

help pleaseeeeee. dbdb​

Answers

Answer:

no way

Explanation:

more free points

YOU MUST SHOW YOUR WORK FOR FULL CREDIT!
1. Jimmy picks up a 5kg box and places it on a shelf 1 meter from the ground. What is the
gravitational potential energy of the box?

Answers

Answer: 49 joules

Explanation: gravitational potential energy = mgh

m= mass kg,  g= acceleration due to gravity 9.8 m/sec/sec, h= height m

=5*9.8.1 joules = 49 joules

how can I improve my science

Answers

Answer:

1).Accept That There Isn't Always a Right Answer.

2). Figure Out “Why”

3). Participate 100% in Class.

4). Go to office hours

5). Speak Up in Your Group. “ even if the answer is probably not right it’s always good to know that you tried”

6). Find a quiet place to study.

God bless you have have a beautiful blessed day!

Take Notes...

Change It Up...

Take A Study Nap...

Record What You're Memorizing. ...

Write Everything Down. ...

Section Your Notes. ...

Use the Memory Palace Technique. ...

Apply Repetition to Cumulative Memorization. ...

Teach It to Someone. ...

Listen to the Recordings Continuously....

7.00 of Compound x with molecular formula C3H4 are burned in a constant-pressure calorimeter containing 35.00kg of water at 25c. The temperature of the water is observed to rise by 2.316c. (You may assume all the heat released by the reaction is absorbed by the water, and none by the calorimeter itself.) Calculate the standard heat of formation of Compound x at 25c.

Be sure your answer has a unit symbol, if necessary, and round it to 3 significant digits.

Answers

Answer:

[tex]\Delta H_{f,C_3H_4}=276.8kJ/mol[/tex]

Explanation:

Hello!

In this case, since the equation we use to model the heat exchange into the calorimeter and compute the heat of reaction is:

[tex]\Delta H_{rxn} =- m_wC_w\Delta T[/tex]

We plug in the mass of water, temperature change and specific heat to obtain:

[tex]\Delta H_{rxn} =- (35000g)(4.184\frac{J}{g\°C} )(2.316\°C)\\\\\Delta H_{rxn}=-339.16kJ[/tex]

Now, this enthalpy of reaction corresponds to the combustion of propyne:

[tex]C_3H_4+4O_2\rightarrow 3CO_2+2H_2O[/tex]

Whose enthalpy change involves the enthalpies of formation of propyne, carbon dioxide and water, considering that of propyne is the target:

[tex]\Delta H_{rxn}=3\Delta H_{f,CO_2}+2\Delta H_{f,H_2O}-\Delta H_{f,C_3H_4}[/tex]

However, the enthalpy of reaction should be expressed in kJ per moles of C3H4, so we divide by the appropriate moles in 7.00 g of this compound:

[tex]\Delta H_{rxn} =-339.16kJ*\frac{1}{7.00g}*\frac{40.06g}{1mol}=-1940.9kJ/mol[/tex]

Now, we solve for the enthalpy of formation of C3H4 as shown below:

[tex]\Delta H_{f,C_3H_4}=3\Delta H_{f,CO_2}+2\Delta H_{f,H_2O}-\Delta H_{rxn}[/tex]

So we plug in to obtain (enthalpies of formation of CO2 and H2O are found on NIST data base):

[tex]\Delta H_{f,C_3H_4}=3(-393.5kJ/mol)+2(-241.8kJ/mol)-(-1940.9kJ/mol)\\\\\Delta H_{f,C_3H_4}=276.8kJ/mol[/tex]

Best regards!

A compound is made of 6.00 grams of oxygen, 7.00 grams of nitrogen, and 20.00grams of hydrogen. Find the percent composition of the compound.

A O-18.18%, N-21.21%, H-60.60%
B O-11.18%, N-22.21%, H-69.60%
C O-20%, N-30%, H-50%
D O-60.60%, N-21.21%, H-18.18%

Answers

The percent composition of the compound.

A O-18.18%, N-21.21%, H-60.60%

Further explanation

Given

6.00 grams of oxygen,

7.00 grams of nitrogen,

20.00 grams of hydrogen.

Required

The percent composition

Solution

Total mass :

= mass of O + mass of N + mass of H

= 6 + 7 + 20

= 33 g

% O = 6/33 x 100%= 18.18%

% N = 7/33 x 100%=21.21%

% H = 20/33 x 100% = 60.6 %

how is the name of the second element in a covalent molecule changed

Answers

Answer:

See explanation

Explanation:

Here we are trying to see how a binary covalent compound is named. A binary covalent compound comprises of only two elements held together by covalent bonds.

The first element retains its normal name whereas the second element has the suffix -ide added to it.

For instance, CO2 is named as carbon dioxide, HBr is named as hydrogen bromide etc.

Answer: it's ide

Explanation:

Got it right in the quiz

Explain the differences between an ideal gas and a real gas.

Answers

Answer:

Ideal Gas

The ideal gas is extremely small and the mass is almost zero and no volume Ideal gas is also considered as a point mass.

Real Gas

The molecules of real gas occupy space though they are small particles and also have volume.

anation:

The differences between an ideal gas and a real gas are that the ideal gas follows the gas laws perfectly under all conditions. Whereas a real gas deviates from ideal gas behaviors.

The ideal gas law, also known as the general gas equation, is a fundamental principle in thermodynamics and relates the pressure, volume, temperature, and number of moles of an ideal gas.

An ideal gas is a theoretical gas that follows the gas laws perfectly under all conditions of temperature and pressure. It is assumed to have no volume, no intermolecular forces, and elastic collisions between its particles. An ideal gas also obeys the ideal gas law.

On the other hand, a real gas is a gas that does not follow the gas laws perfectly under all conditions of temperature and pressure. Real gases have volume and intermolecular forces that affect their behavior. These forces cause deviations from ideal gas behavior, especially at high pressures and low temperatures.

In summary, while an ideal gas is a theoretical gas that follows the gas laws perfectly under all conditions, a real gas is a gas that deviates from ideal gas behavior due to its volume, intermolecular forces, and non-elastic collisions between its particles.

Learn more about ideal gas law here:

https://brainly.com/question/33342075

#SPJ2

An average reaction rate is calculated as the change in the concentration of reactants or products over a period of time in the course of the reaction. An instantaneous reaction rate is the rate at a particular moment in the reaction and is usually determined graphically, but it can also be calculated using calculus. The reaction of compound A forming compound B was studied and the following data were collected:

Time (s) [A] (M)
0. 0.184
200. 0.129
500. 0.069
800. 0.031
1200. 0.019
1500. 0.016

Required:
a. What is the average reaction rate between 0 and 1500s?
b. What is the average reaction rate between 200. and 1200s ?
c. What is the instantaneous rate of the reaction at t=800s?

Answers

Answer:

Explanation:

a )

Average reaction rate between 0 and 1500s

Time duration = 1500 s

moles reacted = .184 - .016 = .168 moles

Moles reacted per second = .168 / 1500

= 112 x 10⁻⁶ moles /s

b )

Average reaction rate between 200 and 1200s

Time duration = 1000 s

moles reacted = .129 - .019 = .11 moles

Moles reacted per second = .11 / 1000

= 110 x 10⁻⁶ moles /s

c )

the instantaneous rate of the reaction at t=800s

We shall assume that between 500 s and 1200 s , rate of reaction is uniform

rate between 500 and 1200

Time duration = 700 s

moles consumed = .069 - .019 = .05 moles

Rate of reaction = .05 / 700

= 71 .4 x 10⁻⁶ moles / s

This will also be instantaneous rate of reaction at t = 800 s .

Consider the addition of an electron to the following atoms from the fifth period. Rank the atoms in order from the most negative to the least negative electron affinity values based on their electron configurations.
Atom or ion Electron configuration
I [Kr]4d105s25p5
Sn [Kr]4d105s25p2
Xe [Kr]4d105s25p6
Rank the electron affinity from most negative to least negative. To rank items as equivalent, overlap them.

Answers

Answer:

I>Sn>Xe

Explanation:

Electron affinity refers to the ability of an atom to accept electron(s) and form a negative ion.

We know that electron affinity is a periodic trend that increases across the period but decreases down the group.

Hence the, electron affinity of iodine is far higher than that of tin. However, xenon is a noble gas and does not accept electrons. Hence, it has an electron affinity of 0 KJ/mol.

How does the government rely on scientists?

Answers

They rely on scientists for facts and answers

3. How much heat (in kl) is released when 1.65 mol NaOH(s) is dissolved in water? (The molar heat of solution of NaOH is -445.1 kJ/mol.)
a. -1.36x 10-3 kJ
b. -7.34 x 10^2 km
c. -2.69 x 10^1 km
d. -2.80 x 10^2 km

Answers

The heat released : b. -7.34 x 10² kJ

Further explanation

Given

1.65 mol NaOH

The molar heat of solution of NaOH is -445.1 kJ/mol

Required

Heat released

Solution

ΔH solution = Q : n

ΔH solution = enthalpy of solution(-=exothermic, +=endothermic)

Q = heat released/absorbed

n = moles of solute

Input the value :

Q = ΔH solution x n

Q = -445.1 kj/mol x 1.65 mol

Q = -734.415 kJ

Derive the isentropic and isothermal compressibility terms (for an ideal gas) in the most simplified form and compare them.

Answers

Answer:

Isothermal compressibility is different from isentropic compressibility by temperature instead of entropy.

Explanation:

Isothermal compressibility refers to that type of compressibility where volume change takes place at constant temperature whereas isentropic compressibility refers to that in which volume change takes place at constant entropy. Entropy is the measure of a thermal energy of the system per unit temperature that is unavailable for doing useful work.

Select one metal which will displace Sn from a compound and form metallic tin (Sn).
Cu, Cr, Ag, or Hg

Answers

Answer:

Cr

Explanation:

it just is im from Harvard my boy lmk

Helium on the Moon was found to be 0.420% 2He, 2.75% 3He, and 96.83% 4He. What is the average atomic mass of helium on the Moon?

Answers

Answer:

Average atomic mass  = 3.9 amu

Explanation:

Given data:

Percent abundance of He-2 = 0.420%

Percent abundance of He-3 = 2.75%

Percent abundance of He-4 = 96.83%

Average atomic mass = ?

Solution:

Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass) + (abundance of 3rd isotope × its atomic mass)  / 100

Average atomic mass = (0.420×2)+(2.75×3) +(96.83×4)/100

Average atomic mass =  0.84 + 8.25 +387.32 / 100

Average atomic mass = 396.41 / 100

Average atomic mass  = 3.9 amu.

The concentration of urea in a solution prepared by dissolving 16 g of urea in 20 g of H2OH2O is ________% by mass. The molar mass of urea is 60.0 g/mol. The concentration of urea in a solution prepared by dissolving 16 g of urea in 20 g of is ________% by mass. The molar mass of urea is 60.0 g/mol. 44 80 0.80 0.48 0.44

Answers

Answer:

44

Explanation:

Given that :

Mass of solute = Mass of urea = 16g

Mass of water = 20g

Mass of solution = (mass of solute + mass of solvent) = (mass of urea + mass of water) = (16g + 20g) = 36g

Percentage Mass = (mass of solute / mass of solution) * 100%

Percentage Mass = (16 / 36) * 100%

Percentage Mass = 0.4444444 x 100%

Percentage Mass = 44.44%

Percentage Mass = 44%

If 1.546 g of copper was used by a student at the start of the lab, and 0.732 g of copper were obtained at
the end of the series of reactions, what was the percent recovery? Briefly explain how you found your
answer.

Answers

Answer: Percent recovery is 47.34 %

Explanation:

Percent yield is defined as the ratio of experimental yiled to theoretical yield in terms of percentage.

[tex]{\text{ percent yield}}=\frac{\text{amount recovered}}{\text{total amount}}\times 100[/tex]

Putting in the values we get:

[tex]{\text{ percent yield}}=\frac{0.732}{1.546}\times 100=47.34\%[/tex]

Therefore, the percent recovery is 47.34 %

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