Answer:
Heat is released during the process.
Explanation:
From the information provided in question, the enthalpy of formation of water is –285.8 kJ/mol. This is simply an exothermic reaction.
The negative sign indicates that the enthalphy of the reactants is more than the enthalphy of the products and as such, heat is released from the system into the surroundings.
The enthalpy of formation of water is –285.8 kJ/mol means that heat is released during the process.
What is enthalpy of formation of a substance?The enthalpy of formation of a substance is the amount of heat given off or absorbed when one mole of a substance is formed from the reactants.
A positive value for enthalpy means the reaction is endothermic while a negative value for enthalpy means the reaction is endothermic.
Therefore, the enthalpy of formation of water is –285.8 kJ/mol means that the reaction is exothermic and heat is released during the process.
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Calculate the mass (in grams) of hydrogen gas produced when 33.61 g of
diborane (B2H) reacts with excess water.
B Holg) + 6H2O(1)→ 2 H3B03(s) + 6H2(g)
Only enter numerical value without units.
Answer:
14.40g of H2
Explanation:
The balanced equation for the reaction is given below:
B2H6(g) + 6H2O(l) → 2H3BO3(s) + 6H2(g)
Next, we shall determine the mass of B2H6 that reacted and the mass of H2 produced from the balanced equation. This is illustrated below:
Molar mass of B2H6 = (2x11) + (6x1) = 28g/mol
Mass of B2H6 from the balanced equation = 1 x 28 = 28g
Molar mass of H2 = 2x1 = 2g/mol
Mass of H2 from the balanced equation = 6 x 2 = 12g
From the balanced equation above,
28g of B2H6 reacted to produce 12g of H2.
Finally, we shall determine the mass of H2 produced when 33.61g of B2H6 reacted with excess water. This can be obtained as follow:
From the balanced equation above,
28g of B2H6 reacted to produce 12g of H2.
Therefore, 33.61g of B2H6 will react to produce = (33.61 x 12)/28 = 14.40g of H2.
Therefore, 14.40g of H2 were produced from the reaction.
1.1 The elements with the lowest ionization energy of all element are
O The noble gases
O The alkali metals
O The alkaline earth metals
O The halogens
Answer:
O The alkali metalsThe elements with the lowest ionization energy of all element are alakli metals
Explanation:
According to research,
The element with the lowest ionization energy is cesium (Cs). Cesium has atomic number 55 and is in the fifth row of the periodic table.
Caesium is a soft, silvery-golden alkali metal .
To draw a Lewis structure for a polyatomic ion, begin by calculating A, the available electrons, and N, the needed electrons. What is N for CIO3-, the chlorate ion?
Answer:
N for chlorate ion is one
Explanation:
Because N is the number of electrons needed to form octet structure causing a negative charge of one, since it already has 25valence electrons
Answer: 26
Correct Answer
what’s the mass of 0.0485 moles of Na2CO3
Answer:5.1g
Explanation:number of moles of Na2co3 is 0.0485 and it molar mass = 23×2+12+16×3=106
n=m/M
Therefore m= n×M
m= 0.0485×106
=5.141g
The mass of 0.0485 moles of Na2CO3 of 5.141 grams.
What is mass?Mass is defined as a dimensionless number used to describe the mass of a particle or item. Inertia, or the body's resistance to acceleration when a net force is applied, is also measured by this term. The strength of an object's gravitational pull to other bodies is also influenced by its mass. The kilogram serves as the SI's fundamental mass unit. Mass is a physical body's total amount of matter. Gravity and inertia, which are the two main forces influencing how objects move in space, make mass crucial.
Mass can be calculated as
Mass = molar mass x number of moles
Molar mass = 23 x 2 + 12 + 16 x 3
= 106 grams
Mass = 106 x 0.0485
= 5.141 grams
Thus, the mass of 0.0485 moles of Na2CO3 of 5.141 grams.
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Which answer below correctly identifies the type of change and the explanation for the boiling of water?
o physical change because even though the change caused the temperature of the water to
increase, the water's physical properties remained exactly the same
o physical change because even though gas formation was observed, the water was undergoing a
state change, which means that its original properties are preserved
chemical change because gas formation was observed, which indicated that the water was
transformed into a different substance
O chemical change because a temperature change was observed, which indicated that the water
was transformed into a different substance
Answer:
O chemical change because a temperature change was observed, which indicated that the water
Explanation:
I have taken this class
How many molecules are in each sample?
A. 4.9 g H2O
B. 54.4 g N^2
C. 89 g CCI4
D. 11 g C6H12O6
Answer:
To find the number of molecules first find the number of moles.
number of moles (n) = mass / molar mass (M)
then use the formula
N = n × L
where n = number of moles
N = number of entities
L = Avogadro's constant = 6.02 × 10^23entities to find the number of molecules
A. 4.9 g H2O
m = 4.9g
M = (2*1)+(16×1) = 2 + 16 = 18g/mol
n = 4.9/18 = 0.272mol
N = 0.272 × 6.02 × 10^23
= 1.6374*10^23 molecules of H2O
B. 54.4g of N2
m = 54.4g
M(N2) = 14×2 = 28g/mol
n = 54.4/28 = 1.942mol
N = 1.942 * 6.02*10^23
= 1.1690*10^24 molecules of N2
C. 89 g CCI4
m = 89g
M(CCl4) = 12 + (35.5 × 4) = 154g/mol
n = 89/154 = 0.577mol
N = 0.577 × 6.02 × 10^23
= 3.473*10^23 molecules of CCl4
D. 11 g C6H12O6
m = 11g
M(C6H12O6) = (12×6)+(12×1)+(16×6) =
180g/mol
n = 11/180 = 0.0611mol
N = 0.0611 × 6.02×10^23
= 3.678*10^22 molecules of C6H12O6
Hope this helps
Which best explains why a firework being ignited is an example of an exothermic reaction and not an endothermic reaction?
A)The fireworks produce colors.
B)The fireworks give off heat.
C)Igniting the fireworks requires energy
D)Igniting the fireworks makes an odor.
Answer:B
Explanation:
TOOK DA TEST
As the firework releases heat, it is considered as exothermic reaction. The correct option is B.
What is exothermic reaction?An exothermic reaction is one in which the energy required to break bonds in the reactants is less than the energy released when new bonds form in the products.
Energy is constantly released during an exothermic reaction, often in the form of heat. Exothermic reactions characterize all combustion reactions.
Endothermic reactions are chemical reactions that produce products by absorbing heat energy from their surroundings.
Exothermic reactions are important in forensic science, particularly in the investigation of fires and explosions.
Endothermic refers to a chemical reaction that requires heat and results in cooling of the surroundings.
As fireworks are releasing energy in the form of heat, it can be called as an exothermic reaction.
Thus, the correct option is B.
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1. Find the volume ( cm3) of oxygen in: a. 1000cm3 of air b. 50 cm3 of air.
Answer:
A. 210 cm³
B. 10.5 cm³
Explanation:
It is important for us to note that air contains 21% of oxygen, O2. With this idea in mind, let us answer the questions given above.
A. Volume of air = 1000 cm³
Volume of O2 in air =.?
Percentage composition of O2 in air = 21%
Volume of O2 = 21% x 1000
Volume of O2 = 21/100 x 1000
Volume of O2 = 210 cm³
Therefore, the volume of O2 in 1000 cm³ of air is 210 cm³.
B. Volume of air = 50 cm³
Volume of O2 in air =.?
Percentage composition of O2 in air = 21%
Volume of O2 = 21% x 50
Volume of O2 = 21/100 x 50
Volume of O2 = 10.5 cm³
Therefore, the volume of O2 in 50 cm³ of air is 10.5 cm³.
Bird wings and dragonfly wings are both used for flight.
Answer:
Yes
Explanation:
What's the question?
Answer:
yes, they both use it to fllight.
Explanation:
As they are adapted to flight to various places to catch their prey and be safe from various type of harms.
hope it helps..
The diagram show the electron arrangements in the atom of 4 elements.
Which element does NOT form a covalent form?
The element does NOT forms a covalent bond is A
What is covalent Bond ?A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms.
These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding.
Therefore, The element does NOT forms a covalent bond is A
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Which will a positively charged object attract? an object that has a negative charge an object that has a smaller positive charge an object that has no charge an object that has a larger positive charge
Answer:
it will attract an object that has a negative charge
Positively charged objects will attract negatively charged objects.
Law of magnetic attractionsAccording to the law "like charges repel, unlike charges attract', a positively charged substance will repel other positively charged substances.
On the other hand, a positively charged substance will attract every other substance that is negatively charged.
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The products of a reaction are NaCl and H2O. What does the law of conservation of matter reveal about the reactants in the reaction? A. At least some of the reactants will include NaCl and H2O. B. The reactants will contain only Na, Cl, O, and H in some amounts. C. Na, Cl, O, H, and three other elements were the reactant elements. D. The reactants will have one Na, one Cl, one O, and two H atoms.
Answer:
D
Explanation:
total mass should be equal on both sides
it's a double do displacement reaction
HCl + NaOH --> NaCl + H2O
Determine the new pressure of a sample of hydrogen gas if the volume and moles are constant, the initial pressure is 6.0 atm, and it is heated from 15°C to 30.°C. PLEASE HELP ASAP! THANK U SO MUCH!
6.3 atm
5.7 atm
12 atm
3.0 atm
Answer:
6.3 atm.
Explanation:
Data obtained from the question include:
Initial pressure (P1) = 6 atm
Initial temperature (T1) = 15°C = 15°C + 273 = 288K
Final temperature (T2) = 30°C = 30°C + 273 = 303K
Final pressure (P2) =..?
Since the volume and number of mole of the hydrogen gas sample is constant, the following equation will used to obtain the new pressure:
P1/T1 = P2/T2
6/288 = P2 /303
Cross multiply
288 x P2 = 6 x 303
Divide both side by 288
P2 = (6 x 303) /288
P2 = 6.3 atm
Therefore, the new pressure of the hydrogen gas sample is 6.3 atm.
PLEASE HELP ! ! ! Three quantum numbers are derived from Schrodinger’s equation that describe the probability of finding an electron around a nucleus: the principal quantum number, the angular momentum quantum number, and the magnetic quantum number. Define each quantum number.
Answer:
Principle Quantum Number: It describes the size of the orbital and the main energy level. It is represented by n. Where, n = 1,2,3,4....stands for K, L, M, N shell and so on..
Angular momentum Quantum Number : It describes the shape of the orbital. It is represented as 'l'. The value of l ranges from 0 to (n-1). For l = 0,1,2,3... the orbitals are s, p, d, f...
Magnetic Quantum Number : It describes the orientation of the orbitals. It is represented as . The value of this quantum number ranges from . When l = 2, the value of will be -2, -1, 0, +1, +2.
Answer:
Principal Quantum Number: designates the principal electron shell. Angular Momentum Quantum Number-This quantum number determines it's shape of an orbital and thus it's angular distribution. This quantum number determines the number of orbital numbers, their orientation within the sub-shell.
Principal Quantum Number, n
It describes the size of its orbital and of the main energy level. It is represented by n. Where, n = 1,2,3,4....stands for K, L, M, N shell and so on..
ngular Momentum Quantum Number l
It describes the shape of the orbital and thus the angular distribution. It can take from 0 to (n - 1). That is l = 0,1,2,...,(n - 1)
The magnetic Quantum Number, m
It describes the orientation of the orbitals. It is represented as . The value of this quantum number ranges from . When l = 2, the value of will be -2, -1, 0, +1, +2.
Explanation:
Which of the following chemical reactions is reversible?
A. The burning of wood.
OB. The dehydration of copper sulfate (CuSO4).
O C. The neutralization of an acid.
OD. The freezing of water into ice
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