CHEMISTRY HIGH SCHOOL

Consider the reaction of CaC2 and water to produce CaCO3 and NH3 according to the reaction CaCN2 + 3H2O → CaCO3 + 2 NH3 . How much CaCO3 is produced upon reaction of 45 g CaCN2 and 45 g of H2O

Answers

Answer 1

Answer:

Answer:

16.27 g of CaCO3 are produced upon reaction of 45 g CaCN2 and 45 g of H2O.

Explanation:

Ca(CN)2 + 3H2O → CaCO3 + 2 NH3

First of all, let's find out the limiting reactant.

Molar mass Ca(CN)2.

Molar mass H2O: 18 g/m

Moles of Ca(CN)2: mass / molar mass

45 g / 92.08 g/m = 0.488 moles

Moles of H2O: mass / molar mass

45g / 18g/m = 2.50 moles

This is my rule of three

1 mol of Ca(CN)2 needs 3 moles of H2O

2.5 moles of Ca(CN)2 needs (2.5 . 3) / 1 = 7.5 moles

I need 7.5 moles of water, but I only have 0.488. Obviously water is the limiting reactant; now we can work on it.

3 moles of water __ makes __ 1 mol of CaCO3

0.488 moles of water __ makes ___ (0.488 . 1) / 3 = 0.163 moles

Molar mass CaCO3 = 100.08 g/m

Molar mass . moles = mass

100.08 g/m . 0.163 moles = 16.27 g

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What experimental evidence did Thomson have for each statement? A. Electrons have a negative charge.B. Atoms of all elements contain electrons.
When an excited electron in a hydrogen atom falls from ????=5 to ????=2, a photon of blue light is emitted. If an excited electron in an He+ ion falls from ????=4, which energy level must it fall to (????1) for blue light of a similar wavelength to be emitted?
Which of the following nonmetals forms a gas commonly found in our atmosphere? Rn,Cl,I,or N

In a chemical reaction, the mass of the products _____ the mass of the reactants.is greater than
is less than
is equal to
has no relationship to

Answers

Answer: is equal to

Explanation: According to the law of conservation of mass, mass can neither be created nor be destroyed. The mass has to be same on both sides of the reaction and to make this happen, the number of atoms of every element must be equal in reactants and products.

$2H_2+O_2\rightarrow 2H_2O$

2 moles of hydrogen weigh= $2* 2g/mol=4g$

1 mole of oxygen weigh = 32 g

Mass of reactants = 36 g

2 moles of water weigh= $2* 18g/mol=36g$

Mass of products = 36 g

Thus mass of reactants = mass of products = 36 g

is equal to. Regardless of the product that you want to keep, since mass is like energy, it can't be created or destroyed. Therefore it always remains the same.

How many grams of O2(g) are needed to completely burn 73.7 g of C3H8(g)?

Answers

The balanced reaction is:

C3H8 + 5O2 = 3CO2 + 4H2O

We are given the amount of C3H8 to be reacted with O2. This will be the starting point of the calculations.

73.7 g C3H8 ( 1 mol C3H8/ 44.1 g C3H8 ) ( 5 mol O2 / 1 mol C3H8 ) ( 32.0 g O2 / 1 mol O2 ) = 267.39 g O2

Answer: 267.2 grams

Explanation:

$C_3H_8+5O_2\rightarrow 3CO_2+4H_2O$

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

$\text{Number of moles of propane}=(73.7g)/(44.1g/mol)=1.67moles$

According to stoichiometry:

1 mole of $C_3H_8$ require 5 moles of $O_2$

Thus 1.67 moles of $C_3H_8$ will require = $(5)/(1)* 1.67=8.35moles$ of $O_2$

Mass of $O_2=moles* {\text {Molar mass}}=8.35moles* 32g/mol=267.2$

Thus 267.2 grams of oxygen are required.

When water evaporates at constant pressure, the sign of the change in enthalpyA. is negative.
B. is positive.
C. depends on the temperature.
D. depends on the volume of the container.
E. does not exist; that is, the enthalpy change is zero.

Answers

B. is positive
H20 (l)--> H20 (g)
when that happens, the heat is absorbed into the liquid to change the state of the liquid to gas; therefore, in order to change to a gaseous state, heat must be a reactant. and so enthalpy is increasing

Atomic energy is the energy _____. in the nucleus of an atom of electrons and their shells in chemical bonds of elements and compounds

Answers

The correct statement to fill the blank would be the first option. Atomic energy is the energy in the nucleus of an atom of electrons and their shells. From the word atomic itself, we can say that this energy is energy within and carried by the atoms.

Answer:

in the nucleus of an atom

Explanation:

A gas of 190 mL at a pressure of 74 atm can be expected to change its pressure when its volume changes to 30.0 mL. Express its new pressure in units of atmospheres.

Answers

Answer : The new pressure of the gas will be, 468.66 atm

Explanation :

Boyle's Law : This law states that pressure of the gas is inversely proportional to the volume of the gas at constant temperature and number of moles.

$P\propto (1)/(V)$ (At constant temperature and number of moles)

or,

$P_1V_1=P_2V_2$

where,

$P_1$ = initial pressure of the gas = 74 atm

$P_2$ = final pressure of the gas = ?

$V_1$ = initial volume of the gas = 190 ml

$V_2$ = final volume of the gas = 30 ml

Now we put all the given values in the above formula, we get the final or new pressure of the gas.

$74atm* 190ml=P_2* 30ml$

$P_2=468.66atm$

Therefore, the new pressure of the gas will be, 468.66 atm

Answer: The new pressure of the gas is 467 atm.

Explanation:

To calculate the new pressure, we use the equation given by Boyle's law. This law states that pressure is inversely proportional to the volume of the gas at constant temperature.

The equation given by this law is:

$P_1V_1=P_2V_2$

where,

$P_1\text{ and }V_1$ are initial pressure and volume.