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2 years ago

5

Ice is lighter and floats in water because it is a crystalline structure in which each water molecule is bonded to a maximum of

four other water molecules by which kind of bond?

1 answer:

jok3333 [9.3K]2 years ago

7 0

The ice is bonded to a max of four other water molecules by hydrogen bonds

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Acetylene burns in air according to the following equation: C2H2(g) + 5 2 O2(g) → 2 CO2(g) + H2O(g) ΔH o rxn = −1255.8 kJ Given

professor190 [17]

Answer: -227 kJ

Explanation:

The balanced chemical reaction is,

$C_2H_2(g)+\frac{5}{2}O_2(g)\rightarrow 2CO_2(g)+H_2O(g)$

The expression for enthalpy change is,

$\Delta H=\sum [n\times \Delta H_f(product)]-\sum [n\times \Delta H_f(reactant)]$

$\Delta H=[(n_{CO_2}\times \Delta H_{CO_2})+ n_{H_2O}\times \Delta H_{H_2O})]-[(n_{C_2H_2}\times \Delta H_{C_2H_2})+(n_{O_2}\times \Delta H_{O_2})]$

where,

n = number of moles

$\Delta H_{O_2}=0$ (as heat of formation of substances in their standard state is zero

Now put all the given values in this expression, we get

$-1255.8=[(2\times -393.5)+(1\times -241.8)]-[(1\times \Delta H_{C_2H_2})+(\frac{5}{2}\times 0)]$

$-1255.8=[(-787)+(-241.8)]-[(1\times \Delta H_{C_2H_2})+(0)]$

$\Delta H_{C_2H_2}=-227kJ$

Therefore, the enthalpy change for $C_2H_2$ is -227 kJ.

7 0

2 years ago

Enter the symbol of a sodium ion, Na+, followed by the formula of a sulfate ion, SO42−. Separate the ions with a comma only—spac

gladu [14]

Na⁺,SO₄²⁻ is the answer

<h3>Further explanation </h3>

An ion is an atom or molecule that has a net electrical charge. There are many ions, one of them are sodium ion and sulfate ion.

SO₄²⁻ or Sulfate is a naturally occurring polyatomic ion that consist of a central sulfur atom surrounded by four oxygen atoms with occured widely in everyday life. Sodium ions are important for regulation of blood and body fluids, transmission of nerve impulses, heart activity, and certain metabolic functions.

Whereas Na⁺ or Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sulfate ion is a very weak base. Therefore sulfate ion undergoes negligible hydrolysis in aqueous solution.

Enter the symbol of a sodium ion, Na⁺, followed by the formula of a sulfate ion, SO₄²⁻. Separate the ions with a comma only—spaces are not allowed. Express your answers as ions separated by a comma. Therefore the answer is: Na⁺,SO₄²⁻

Hope it helps!

<h3>Learn more</h3>

Learn more about sodium ion brainly.com/question/6839866
Learn more about sulfate ion brainly.com/question/2763823
Learn more about ions brainly.com/question/11852357

<h3>Answer details</h3>

Grade: 9

Subject: Chemistry

Chapter: Introduction to Mastering Chemistry

Keywords: sodium ion, sulfate ion, ions, Chemistry, symbol

6 0

2 years ago

Read 2 more answers

Tamara is doing a scientific investigation to answer the question, "Do corn seeds germinate faster at warmer temperatures than t

sashaice [31]

Answer:

The tools/instruments, the type of seed, the soil or planting products, the amount of germination time/days, and where the seedling is placed.

Explanation:

If anything but the temperature is changed, it can result in false results. For instance, if Tamera uses red corn for one but yellow corn for the other, it can change the germination rate. So can the type of soil, water or the amount of time each plant has to grow. If she changes thermometers or any other tool she uses, it may give her a different result than the ones she used before. And finally, if she moves the warm plant from the windowsill to her bedroom, it can mess with the results she gets from the heated sample.

8 0

2 years ago

The potential energy diagram for a reaction starts at 180 kJ and ends at 300 kJ. What type of reaction does the diagram best rep

aleksklad [387]

Answer: Endothermic reaction

Explanation:

Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and $\Delta H$ for the reaction comes out to be negative.

Endothermic reactions are defined as the reactions in which energy of the product is greater than the energy of the reactants. The total energy is absorbed in the form of heat and $\Delta H$ for the reaction comes out to be positive.

As the energy of reactants is 180 kJ and that of products is 300 kJ, the energy of products is greater than that of reactants, which means the energy has been absorbed and reaction is endothermic.

8 0

2 years ago

Calculate the freezing point of a 0.100 m aqueous solution of k2so4, taking interionic attractions into consideration by using t

Leokris [45]

Ionic salt dissociate completely in water particularly in water at low concentration.
The molal freezing point of depression constant for water is 1.85kg/k/mol
therefore depression of freezing point =1.853 x 0.100 x 2.32=0.429 degrees celsius
hence solute freeze at - 0.429 degree celsius

3 0

2 years ago