Answer:
Reaction B is exothermic
Explanation:
From the context of thermodynamics, chemical reactions can be broadly classified as endothermic and exothermic reactions.
Endothermic reactions involve absorption of energy and show a positive value for the reaction enthalpy i.e. ΔH is positive. In contrast, exothermic reactions are accompanied by the release of energy and show a negative value for the enthalpy change i.e. ΔH is negative.
In a given chemical reaction energy is required to break bonds and it is released during the formation of new bonds.
The Reaction B is such that, the energy required to break bonds is less than energy released during formation bonds. Therefore, since there is a net release of energy, the reaction is exothermic.
Exothermic Reactions
A. outer core.
B. outer mantle.
C. asthenosphere.
D. lithosphere.
lithosphere (its a part of the Crust)
c. Sodium
b. Chromium
d. Iron
(1) argon (3) chlorine
(2) bromine (4) sulfur
Answer: Option (2) is the correct answer.
Explanation:
STP means standard temperature and pressure.
At STP chlorine exists as a gas, sulfur exists as a solid and argon also exists as a gas.
Whereas bromine exists as a liquid at STP.
Thus, we can conclude that out of the given options bromine is the element which exists as a liquid at STP.
The element that is a liquid at standard temperature and pressure (STP) is bromine (Br). Therefore, option 2 is correct.
Bromine is the only element among the options given that is a liquid at STP. It is a reddish-brown liquid with a strong and unpleasant odor. Bromine is a halogen and exists as diatomic molecules (Br₂).
It has a boiling point of 58.8°C (137.8°F) and a melting point of -7.2°C (19.0°F). Bromine is significantly more reactive than argon but less reactive than chlorine and sulfur.
Argon (Ar) is a noble gas and exists as a colorless and odorless gas at STP. Chlorine (Cl) is a greenish-yellow gas at STP. Sulfur (S) is a solid at STP and melts at a relatively high temperature.
To learn more about the element, follow the link:
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Answer:
Answer in picture
Explanation:
To calculate the molar mass of a compound, sum the atomic masses of all atoms in the compound. Ammonia has a molar mass of 17.04 g/mol, magnesium hydroxide has a molar mass of 58.33 g/mol, and iron(III) oxide has a molar mass of 159.70 g/mol.
Calculating Molar Mass
To calculate the molar mass of a compound, you sum the atomic masses of each individual element present in the compound, multiplied by the number of each of those atoms in the formula.
Ammonia (NH3): The atomic mass of nitrogen (N) is approximately 14.01 g/mol and hydrogen (H) is approximately 1.01 g/mol. Since ammonia contains one nitrogen atom and three hydrogen atoms, its molar mass would be (14.01 g/mol) + 3 × (1.01 g/mol) = 17.04 g/mol.
Magnesium hydroxide (Mg(OH)2): The atomic mass of magnesium (Mg) is approximately 24.31 g/mol, oxygen (O) is approximately 16.00 g/mol, and hydrogen (H) is again 1.01 g/mol. Magnesium hydroxide has one magnesium atom, two oxygen atoms, and two hydrogen atoms. Thus, its molar mass is (24.31 g/mol) + 2 × (16.00 g/mol) + 2 × (1.01 g/mol) = 58.33 g/mol.
Iron(III) oxide (Fe2O3): The atomic mass of iron (Fe) is approximately 55.85 g/mol and oxygen (O) is 16.00 g/mol. Iron(III) oxide consists of two iron atoms and three oxygen atoms, giving a molar mass of 2 × (55.85 g/mol) + 3 × (16.00 g/mol) = 159.70 g/mol.
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Cu(s) + S(s) CuS(s)
C6H12O6(s) + 6O2(g) 6CO2(g) + 6H2O(g)
5C2O42-(aq) + 2MnO4-(aq) + 16H+(aq) 10CO2(g) + 2Mn2+(aq) + 2H2O(l)
Ag+(aq) + I-(aq) AgI2(s)
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Answer : Option A) .
Explanation : The reaction of hydrogen gas with iodine in solid phase will react most rapidly at standard conditions.
A rapid chemical reaction is one where reactants react fast with each other to give the products at the standard temperature and pressure conditions.
In the given choices Iodine is highly reactive as it belongs to the halogen group and also atomic hydrogen is very reactive in nature, when both combine it gives hydrogen iodide which is much stable in nature than the reactants.
when one mole of hydrogen reacts with one mole of iodine it produces 2 moles of hydrogen iodide.
.
The reaction between ethanol and oxygen must be a combustion reaction to give carbon dioxide and water as products.
The reaction between ethanol, and oxygen, is as follows:
In order to balance the reaction (the number of atoms of each element in the reaction are same on both the sides that is product and reactant), is multiplied by 3 in the reactant side and is multiplied by 2 and is multiplied by 3 on product side.
So, the balanced reaction is:
From the balanced reaction it is clear that 1 mole of reacts with 3 moles of to give 2 moles of and 3 moles of .
Since, 1 mole = molecules (Avogadro's number)
So,
Number of molecules of = molecules.
Number of molecules of = molecules.
Number of molecules of = molecules.
Number of molecules of = molecules.
Answer : The number of molecules of are 2, 3, 1 and 3 respectively.
Explanation :
The given balanced chemical reaction is,
Balanced chemical reaction is the reaction in which the number of atoms of an individual elements present on reactant side must be equal to the product side.
The species present on the left side of the right arrow is the reactant and the species present on the right side of the right arrow is the product.
From the balanced chemical reaction, we conclude that there are 1 molecule of , 3 molecules of , 2 molecules of and 3 molecules of .