Answer: The number of moles of excess reagent left is 0.750 moles
Explanation:
The number of moles is calculated by using the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
For KI:Given mass of [tex]KI[/tex] = 249 g
Molar mass of [tex]KI[/tex] = 166 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of KI}=\frac{249g}{166g/mol}=1.5mol[/tex]
For [tex]Pb(NO_3)_2[/tex]:Given mass of [tex]Pb(NO_3)_2[/tex] = 496.5 g
Molar mass of [tex]Pb(NO_3)_2[/tex] = 331 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of }Pb(NO_3)_2=\frac{496.5g}{331g/mol}=1.5mol[/tex]
The given chemical equation follows:
[tex]2KI+Pb(NO_3)_2\rightarrow 2KNO_3+PbI_2[/tex]
By stoichiometry of the reaction:
If 2 moles of KI reacts with 1 mole of lead(II) nitrate
So, 1.5 moles of KI will react with = [tex]\frac{1}{2}\times 1.5=0.75mol[/tex] of lead(II) nitrate
As the given amount of lead(II) nitrate is more than the required amount. Thus, it is present in excess and is considered as an excess reagent.
Thus, KI is considered a limiting reagent because it limits the formation of the product.
Moles of excess reactant ([tex]Pb(NO_3)_2[/tex]) left = [1.5 - 0.75] = 0.750 moles
Hence, the number of moles of excess reagent left is 0.750 moles
Pure hydrogen (H₂) is a hazardous substance. Thus, safer and more cost effective techniques have been developed to store it as a solid for shipping purposes. One such method is the reaction below, which occurs at 200 °C.
Answer: hello your question has some missing details attached below is the missing details
answer : 25.5% ( B )
Explanation:
Determine percentage yield
molar mass = 35 g/mol
mass of Li₃N(s) = 70 g
product LiH(s) = 8.0 g ( actual yield )
theoretical yield ( LiH ) = 4 * 7.95 = 31.8 g
percentage yield = actual yield * 100 / theoretical yield
= 8 * 100/31.8
= 25.5%
If I threw a block of sodium into a lake, and the H2 created took up 34 L of space at STP (standard temperature and pressure: 1 atm and 0C), how many grams of Na did I begin with?
Answer:
70g Na
Explanation:
The sodium reacts with water as follows:
2Na + 2H2O → 2NaOH + H2
Where 2 moles of Na produce 1 mole of H2.
To solve this question we must find the moles of H2. With the balanced equation we can find the moles of Na and its mass as follows:
Moles H2:
PV = nRT; n = PV/RT
Where P is pressure = 1atm,
V is volume = 34L,
R is gas constant = 0.082atmL/molK
T is absolute temperature = 273.15K = 0°C
Replacing:
n = 1atm*34L/0.082atmL/molK*273.15K
n = 1.52 moles H2
Moles Na:
1.52 moles H2 * (2mol Na / 1mol H2) = 3.04 moles Na
Mass Na-Molar mass: 22.99g/mol-
3.04 moles Na * (22.99g / mol) =
70g NaWhich of these takes place when a chemical change occurs? option 1: Bonds connecting atoms in products and reactants form. option 2: Bonds connecting atoms in products and reactants break. option 3: Bonds connecting atoms in reactants break, and bonds connecting atoms in products form. option 4: Bonds connecting atoms in reactants form, and bonds connecting atoms in products break.
Answer: Out of the given options bonds connecting atoms in reactants break, and bonds connecting atoms in products form are the changes which takes place when a chemical change occurs.
Explanation:
A change that leads to the change in chemical composition of a substance is called a chemical change.
For example, [tex]2NH_{3} \rightarrow N_{2} + 3H_{2}[/tex]
Here, bond between the reactant atoms nitrogen and hydrogen is broken down.
On the other hand, bond connecting the products that is [tex]N_{2}[/tex] and [tex]H_{2}[/tex] is formed.
Thus,, we can conclude that out of the given options bonds connecting atoms in reactants break, and bonds connecting atoms in products form are the changes which takes place when a chemical change occurs.
The reaction of hydrogen with nitrogen to produce ammonia is shown below. If there are 3 moles of nitrogen, how many moles of hydrogen are needed to react completely with the nitrogen?
Answer:
9
Explanation:
I took the same test :)
The stoichiometry is important in chemistry which helps us to use the balanced equation to calculate the amount of reactants and products. Here the moles of hydrogen needed is 9. The correct option is B.
What is stoichiometry?The quantitative study of the reactants and products involved in a chemical reaction is known as the chemical stoichiometry. The stoichiometric coefficients can be fractions including the whole numbers. It helps to establish the mole ratio.
The stoichiometric coefficient is basically the number which is present in front of the atoms, molecules or ions. The stoichiometric calculations are also used in gravimetry and volumetry.
Here the balanced equation for the reaction is:
N₂ + 3H₂ → 2NH₃
Number of moles of H₂ = 3 mol N₂× 3 mol H₂ / 1 mol N₂ = 9 mol H₂
So the number of moles of H₂ is 9.
Thus the correct option is B.
To know more about stoichiometry, visit;
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What type of experiment did the student in the passage perform?
Answer:
Passage?
Explanation:
Please help! I don't know how to do and want to understand
Cells can regulate different processes in two ways. They can turn on and off the genes that make enzymes, or they can
A)
increase the activation energy of a reaction.
B)
increase the amount of energy needed to carry out the preferred process.
C)
regulate the enzymes that are already made.
D)
decrease the amount of energy needed to carry out the preferred process.
Answer:
im pretty sure its d
Explanation:
Indica en qué modelos se fueron descubriendo las partículas atómicas y las unidades en la que se expresan su masa y su carga eléctrica
Answer:
En total son 8 modelos, en la explicación los nombraremos por orden de antigüedad.
Explanation:
Modelo atómico de Demócrito (450 a.C.)
Modelo atómico de Dalton (1803 d.C.)
Modelo atómico de Lewis (1902 d.C.)
Modelo atómico de Thomson (1904 d.C.)
Modelo atómico de Rutherford (1911 d.C.)
Modelo atómico de Bohr (1913 d.C.)
Modelo atómico de Sommerfeld (1916 d.C.)
Modelo atómico de Schrödinger (1926 d.C.)
what do u mean by change in state of matter?define it.
Answer:
The mode of changing from one state of matter into another state and back to the former or original state is called change in state of matter .
hope it is helpful to you
Answer:
change in one state from another and back in its own original is known as change in state of matter
What makes plants the beginning of the food chain?
please answer my question aswell as my last one!
Answer: A
Explanation:
i just took the quiz and it was right!
Which of these is an example of a prosthesis?
A. A hearing aid
B. A textbook
C. Gloves
D. A pair of boots
Answer:
hearing aid
Explanation:
an artificial body part
A hearing aid is an example of a prosthesis. Therefore, option A is correct.
A prosthesis is an artificial device or replacement for a missing body part or function. In the case of a hearing aid, it is a device designed to assist people with hearing loss by amplifying sound. It acts as a substitute for the natural function of the ear.
A textbook is a written educational resource, gloves are protective coverings for the hands, and a pair of boots is footwear. These items do not serve as artificial replacements for missing body parts or functions.
To learn more about the prosthesis, follow the link:
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An inverse relationship can be represented by what?
Answer:
1/....
Explanation:
If we say acceleration 'a' is inversely proportional to mass 'm', then
a=1/m.
How long is radioactive waste from nuclear plants radioactive?
1.) 100,000 years
2.) 10,000 years
3.) 100 years
4.) 1,000 years
Please answer. Brainliest!
The equation is balanced.
Explanation:The number of P atoms in the reactant side is 4 and the number of P atoms in the product side is also 4.
The number of O atoms in the reactant side is 16 and the number of O atoms in the product side is also 16.
The number of H atoms in the reactant side is 12 and the number of H atoms in the product side is also 12.
These results are in accordance with the law of conservation of mass.
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Why increasing the temperature of a gas would increase the volume of its container in gas law?
When the amount of gas in a container is increased, the volume increases. Lussac's law states that the pressure of a given amount of gas held at constant volume is directly proportional to the Kelvin temperature.
Is soup pure or impure?
Answer:
I think it's impure . Hope this helps you
Answer:
I think is pure but not 100% pure.
This woman comes to the clinic with high blood pressure,
hyperglycemia(high blood sugar), weakening of the bones and severe
depression of the immune system. Can you diagnose her condition?
The radius of the large cylinder of a hydrolic press
20cm and that of the small cylinderis 5 cm. If a force of 100N is applied on the small piston Calculate the force on the large piston. if the piston of the small cylinder move through a distance of 0.4m through what distance can the large piston be raised
Answer: 1) 400N
2)1.6
Explanation:
1) 5cm = 100N of force
so
20cm=400n
2) 0.4 X 4 = 1.6
125 cm3 of a solution contains 0.25 moles of the solute. What is the concentration of the solution?
Answer:
Explanation:
125 cm3 -> 0.125 L
M = no. mole / volume (L)
M = 0.25 / 0.125 = 2 M
. If you have 5.42 x 1024 aluminum atoms, approximately how many moles is that?
Please help me
Answer:
5.42x10^24 atoms/1 x 1 mole/6.022x10^23
= 9.5 mol
Which electron in an atom (Z=17) is the most shielded from
nuclear charge?
A. an electron in the 2s
B. an electron in the 3p
C. an electron in the 3d
D. an electron in the 1s
Answer:
option no. C is correct
an electron in the 3d
Explain why the buffering action of these chemical reactions is limited by the present day rate of change for atmospheric CO2 concentration
Answer:
Due to increase in carbondioxide gas.
Explanation:
The buffering action of these chemical reactions is limited by the present day rate of change for atmospheric carbondioxide concentration because the the rate of atmospheric carbondioxide rises as compared to ancient atmospheric carbondioxide gas. Due to increase of human activities, the concentration of carbondioxide gas increases in the atmosphere which limits the buffering action of these chemical reactions so we can say that carbondioxide gas is responsible for its limited action.
Will give brainliest
Process name of water vapor to ice
Answer:
Deposition
this is the process of a substance changing its state from gas to solid. Solid to gas is known as sublimation
An unknown substance weighing 42.0 g was heated from 36.0°C to 65.0°C. In this process, the
substance absorbed 5895 J of energy. What is the specific heat of the substance?
A. 5895 J/(g*C)
B. 4.18 J/(g*C)
C. 4.84 J/( g*C)
D. O.06 J/(g*C)
Answer:
A. 5895 J/g*C)
Explanation:
An unknown substance weighing 42.0 g was heated from 36.0°C to 65.0°C. In this process, the substance absorbed 5895 J of energy.
Aluminum reacts with oxygen to form aluminum oxide. Select the correct unbalanced skeleton equation for this reaction. A. Al(s) + 0(g) - AIO(s) B. Al203(s) - Al(s) + 02(8) C. Al(s) - 02(8) + Al203(s) D. Al(s) + 02(8) - Al203(s)
Answer:
D. Al(s) + O₂(g) → Al₂O₃(s)
Explanation:
Aluminum is a solid metal, so it is written as Al(s).
Oxygen is a diatomic gas, so we write this compound as O₂(g).
Aluminum oxide has the formula Al₂O₃ because in oxides the oxidation number of oxygen atom is -2 and for aluminum, the oxidation number is 3. Thus, we write this compound as Al₂O₃(s).
Now, we have to found the chemical equation in which the reactants (left side) are Al(s) and O₂(g) while the product (right side) is Al₂O₃(s). From the options, we can see that the correct is (D):
Al(s) + O₂(g) → Al₂O₃(s)
How many grams of calcium chloride would you measure if you needed to
add 0.125 moles of calcium chloride to 100mL of water?
Answer: cuhh
Explanation:
In its aqueous solution, 32% of a substance dissociates to release hydroxide ions. Which of the following is true for the substance? (3 points)
It is a weak acid
It is a weak base.
It is a strong acid
It is a strong base.
*please only answer is you have the real answer bc I really need to bring up my grade*
Answer:
It is a weak base.
Explanation:
A base is a substance that releases hydroxide ion (OH-) when in an aqueous solution, according to Svante Arrhenius definition of a base. However, a base is said to be either strong or weak depending on it is able to dissociate.
A weak base is a base that does not completely dissociate into hydroxide ions in an aqueous solution while a strong base dissociates completely. According to this question, 32% of a basic substance ( because it can dissociate into OH-) dissociates to release hydroxide ions. This means that since it does not totally dissociate i.e. 100%, it is a WEAK BASE.
Answer:
It is a weak base.
Explanation:
Guy above me is right and I took the test :)
The skin has and needs natural oils. Why is it advisable
to wear gloves while working with strong alkalis ?
Answer:
As we know that alkalis react with oil to form soap. As our skin contains oil so when we touch strong alkalis, a reaction takes place and the soapy solution is formed. Hence we should wear gloves.
Answer:
As we know that alkalis react with oil to form soap. As our skin contains oil so when we touch strong alkalis, a reaction takes place and the soapy solution is formed. Hence we should wear gloves.
Explanation:
it from internet
La columna de la izquierda corresponde a los tipos de sales y la columna derecha a los tipos de fórmula que presentan. Relacionar con el mismo COLOR las parejas correspondientes. 1. Hidracidas a. MX 2 Acidas b. MXO 3. Oxacidas c. MHXO 4. Basicas d. M(OH)XO
Answer:
1. Hidracidas a. MX
2 Acidas c. MHXO
3. Oxacidas b. MXO
4. Basicas d. M(OH)X
Explanation:
¡Hola!
En este caso, de acuerdo con el concepto de sal, la cual está generalmente dada por la presencia de al menos un metal y un no metal, es posible encontrar cuatro tipos de estas; hidrácidas, oxácidas, básicas y ácidas, en las que las primeras dos son neutras pero la segunda tiene presencia de oxígeno, la tercera tiene iones hidróxido adicionales y la cuarta iones hidrógeno de más.
Debido a la anterior, es posible relacionar cada pareja de la siguiente manera:
1. Hidracidas a. MX
2 Acidas c. MHXO
3. Oxacidas b. MXO
4. Basicas d. M(OH)XO
En las que M se refiere a un metal, X a un no metal, H a hidrógeno y O a oxígeno.
¡Saludos!
help bc i need it lol
Answer:
2 XE + 1 AB. --> 1 AE2 + 2 XB
Above equation is now balanced
