Which elements make up a water molecule?

hydrogen and nitrogen
oxygen and nitrogen
oxygen and carbon
hydrogen and oxygen

Answer:

Endothermic reaction

Explanation:

Baking a bake batter in an oven is a typical endothermic reaction because it absorbs heat to drive a chemical change.

The heat changes that accompanies a chemical reaction can be categorized as either exothermic or endothermic.

In baking a cake batter, the oven furnishes it with a high temperature which drives a chemical change there in. This kind of reaction that absorbs energy from the environment is an endothermic reaction.

Answer:

Sample Response: Baking a cake requires heat to be applied to the batter in order for it to cook and chemically change into cake. The energy or heat applied is absorbed by the ingredients, so this represents an endothermic reaction.

Answer:

C. Combustion

Explanation:

Combustion- an organic compound containing carbon, hydrogen and sometimes oxygen reacts  with oxygen gas to form carbon dioxide and water.

Answer:

Heating.

Cooling.

Water Heater.

Washer and Dryer.

Lights.

Refrigerator.

Electric Oven.

Dishwasher.

Charging devices

Explanation:

People use electricity for lighting, heating, cooling, and refrigeration and for operating appliances, computers, electronics, machinery, and public transportation systems.

How it works is a current of electricity is a steady flow of electrons. When electrons move from one place to another, round a circuit, they carry electrical energy from place to place like marching ants carrying leaves. Instead of carrying leaves, electrons carry a tiny amount of electric charge

Hope this helped some!

Answer: microwave, TV, lamps, refrigerator, and last but not least a stove.

Answer:

There are 0.239 moles of water in 1.44 x 10^23 molecules

Explanation:

We use the Avogadro´s Number, whereby in 1 mole of any substance there are 6, 023x10e23 molecules:

6, 023x10e23 molecules-----1 mol water

1.44 x 10^23 molecules -----x=

x= ( 1.44 x 10^23 molecules x 1 mol water)/6, 023x10e23 molecules

x=0,239 mol water

Answer

7.2 g of Oxygen are needed to produce 0.400 mole Fe₂O₃ in the following reaction

Explanation:

4 Fe(s) + 3O₂= 2 Fe₂O₃(s)

4 moles of Fe reacts with 3 moles of oxygen to give 2 moles of Fe₂O₃

to get the grams of oxygen needed to produce 0.400 mole Fe₂O₃ in the following reaction

we first get the moles then convert it to grams

3 moles of oxygen are needed to give 2 moles of Fe₂O₃ in the equation thus we have 3:2

let the represent the moles of oxygen that will be intended for 0.400 mole Fe₂O₃ in the following reaction

x:0.4

3:2=x:0.4

3/2 = x/0.4

cross multiply

3x0.4 = 2x

1.2 = 2x

x= 1.2/2 = 0.6

moles is 0.6

1 mole of Oxygen is 12g of Oxygen

0.6 mole of oxygen will give = 0.6 x12= 7.2 g of Oxygen

7.2 g of Oxygen are needed to produce 0.400 mole Fe₂O₃ in the following reaction

To produce 0.400 moles of Fe₂O₃, 95.8 g of O₂ are needed.

Let's consider the following balanced equation.

4 Fe(s) + 3 O₂(g) ⇒ 2 Fe₂O₃(s)

We can calculate the grams of O₂ needed to produce 0.400 moles of Fe₂O₃ considering the following relationships.

[tex]0.400molFe_2O_3 \times \frac{159.69gFe_2O_3}{1molFe_2O_3} \times \frac{3molO_2}{2molFe_2O_3} = 95.8 gO_2[/tex]

To produce 0.400 moles of Fe₂O₃, 95.8 g of O₂ are needed.

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How many grams of O₂ are needed to produce 0.400 mole Fe₂O₃ in the following reaction?

4 Fe(s) + 3 O₂(g) ⇒ 2 Fe₂O₃(s)

Answer:

A

Explanation:

B is incorrect because asexual reproduction produces an offspring exactly the same as it's parent. Thus the probability does not need to be calculated.

C and D logically do not make sense since B is incorrect and A is correct. I provided the explanation why it is incorrect above.

Thus A is the correct answer.

_________________________________________________

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Answer :

(4) The mass of NaCl needed would be, 172.2 grams.

(5) The molality of toluene in the solution is, 10.9 mol/kg

Explanation :

Part 4:

[tex](K_b)[/tex] for water = [tex]0.5100^oC/m[/tex]

[tex]\Delta T_b=1.500^oC[/tex]

Mass of water (solvent) = 1001 g  = 1.001 kg

Molar mass of NaCl = 58.5 g/mole

Formula used :  

[tex]\Delta T_b=i\times K_b\times m\\\\\Delta T_b=i\times K_b\times\frac{\text{Mass of NaCl}}{\text{Molar mass of NaCl}\times \text{Mass of water in Kg}}[/tex]

where,

[tex]\Delta T_b[/tex] = change in boiling point

i = Van't Hoff factor = 2  (for NaCl electrolyte)

[tex]K_b[/tex] = boiling point constant for water

m = molality

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

[tex]1.500^oC=2\times (0.5100^oC/m)\times \frac{\text{Mass of NaCl}}{58.5g/mol\times 1.001kg}[/tex]

[tex]\text{Mass of NaCl}=172.2g[/tex]

Therefore, the mass of NaCl needed would be, 172.2 grams.

Part 5:

Formula used :

[tex]\text{Molality}=\frac{\text{Mass of toluene}\times 1000}{\text{Molar mass of toluene}\times \text{Mass of benzene (in g)}}[/tex]

Given:

Mass of toluene = 80.1 g

Mass of benzene = 80.0 g

Molar mass of toluene = 92.13 g/mol

[tex]\text{Molality}=\frac{80.1g\times 1000}{92.13g/mole\times 80.0g}=10.9mole/kg[/tex]

Therefore, the molality of toluene in the solution is, 10.9 mol/kg

Answer:

So, the three conditions for a chemical reaction to occur are: Temperature should be above absolute zero. Chemical reactants must be in close, proximate, physical contact. The reaction must have negatie free energy (exergonic) and the system must provide it sufficient energy to overcome the Activation Energy Barrier.

Answer: double-replacement reaction

Explanation:

Answer:

0.97 mole

Explanation:

1 mole will give 6.02×10^23 atoms

Xmole of tungsten will give 5.82×10^23 atom of tungsten

X= 5.82×10^23/ 6.02×10^23

X = 0.97 moles of tungsten

Answer:

0.967 moles

Explanation:

number of moles = number of atoms / avogadro's number

We are given;

Number of atoms = 5.82×10^23

Avogadro's number = 6.02×10^23

Therefore, number of moles

= (5.82×10^23)/(6.02×10^23)

=0.967mol

Therefore, 0.967 moles are equal to 5.82×10^23 atoms

Answer:

[H3O+] = 4.5 x 10^-3 M

[OH-] = 1.0 x 10^-14 / 4.5 x 10^-3 =2.2 x 10^-12 M

pH = - log [H3O+]= - log 4.5 x 10^-3 =2.3

A solution contains 4.5 × 10⁻⁵M HCl so the concentration of hydronium ion is 4.5 × 10⁻⁵M, pH of the solution is 4.34 and concentration of hydroxide ion is 2.2 × 10⁻⁸M.

pH of any solution will be calculated as pH = -log[H⁺], where

[H⁺] = concentration of H⁺ or H₃O⁺ ion

Given concentration of HCl = 4.5 × 10⁻⁵M

HCl is a strong acid so that it completely dissociates into their ions as:
HCl → H⁺ + Cl⁻

From the stoichiometry, 1 mole of HCl produces 1 mole of H⁺ ion.

Concentration of H⁺ ion = 4.5 × 10⁻⁵M

Now we calculate pH by using the concentration value as:
pH = -log(4.5 × 10⁻⁵)

pH = -(-4.34) = 4.34

Also we know the relation:

[H⁺][OH⁻] = 10⁻¹⁴

[OH⁻] = 10⁻¹⁴ / 4.5 × 10⁻⁵ = 2.2 × 10⁻⁸M

Hence required values are (a)4.5 × 10⁻⁵M, (b)4.34 and (c)2.2 × 10⁻⁸M.

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Answer:

ΔS(23g NH₃) = 132.2 j/K  ≅ 130 j/K (~2 sig. figs. based on 2 sig. figs. in 23 grams NH₃).

Explanation:

Given ΔHv(NH₃) = 23.4 Kj/mol = 23,400 joules/mole

T = -33.5°C = (-33.5 + 273)K = 239.5K

molar ΔS (at boiling) = ΔHv/T = 23,400 j/mol / 239.5K = 97.70 j/mol·K

ΔS(23g NH₃) = molar ΔS (at boiling) x (moles NH₃) = 97.70j/mol·K  x  (23g/17g·mol⁻¹) = 132.2 j/K ≅ 130 j/K (~2 sig. figs. based on 2 sig. figs. in 23 grams NH₃).

The change in entropy when 23 g of ammonia boils at -33.5 °C is 0.178 kJ/K. To find this, the mass of ammonia was converted to moles, the given temperature was converted to Kelvin, and then the heat of vaporization was divided by the temperature.

To calculate the change in entropy (ΔS) when 23 g of ammonia boils at -33.5 °C, we'll use the heat of vaporization (ΔHv) of ammonia, which is 23.4 kJ/mol. First, we convert the given mass of ammonia to moles by using its molar mass (17.03 g/mol for NH3). This gives us:

23 g / 17.03 g/mol = 1.351 moles of ammonia.

Next, we use the formula ΔS = ΔHv / T, where T is the temperature in kelvin.

Since the boiling occurs at -33.5 °C, we first need to convert this temperature to Kelvin:

T = -33.5 °C + 273.15 = 239.65 K.

The total change in entropy for the vaporization of ammonia is then:

ΔS = (23.4 kJ/mol × 1.351 mol) / 239.65 K,

ΔS = 31.61 kJ / 239.65 K = 0.1318 kJ/K × 1.351 = 0.178 kJ/K (or 178 J/K).

This is the change in entropy for the given amount of ammonia with the correct number of significant digits and units.

Answer:

241.82 kJ is released

Explanation:

The reaction indicates that 483.64 kJ of energy is released when TWO moles of H2O(g) is formed. You're looking to find the amount of energy released when only ONE mole of H2O forms, so that would be half the amount of energy released in the reaction (as one mole is a half of two).

483.64 / 2 = 241.82 kJ

So, your answer would be 241.82 kJ is released.

The formation of 1 mole of water (H_2O) in the given chemical reaction releases 241.82 kJ of energy.

The reaction described in the question, 2H_2(g) + O_2(g) -> 2H_2O(g) with ΔHrxn = -483.64 kJ, shows that the formation of 2 moles of water (H_2O) releases 483.64 kJ of energy.

It's an exothermic reaction, meaning energy is released. That said, if we want to find out the amount of energy released during the formation of 1 mole of water, we divide the total energy by 2.

Thus, the formation of 1 mole of water (H_2O) releases 483.64 kJ / 2 = 241.82 kJ of energy.

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Answer:

1600 calories

Explanation:

Data obtained from the question include:

M (mass of water) = 20g

T1 (initial temperature) = 383°C

T2 (final temperature) = 303°C

ΔT (change in temperature) = T1 - T2 = 383 - 303 = 80°C

C (specific heat capacity of water) = 1 calorie/g°C

Q (heat) =?

Using the the equation Q = MCΔT, the heat in calories absorbed by the water can be obtained as follow:

Q = MCΔT

Q = 20 x 1 x 80

Q = 1600 calories

Therefore, the heat absorbed by the water is 1600 calories

Answer:

elements

Explanation:

Answer:

100g like you answered it yourself

Explanation:

The two main postulates that was given by Antoine Lavoisier are, oxygen play an important role in combustion and the other is mass of the reactant and product is conserved. The total mass of reactant must be equal to total mass of product.

According to Law of conservation of mass, mass can neither be created nor be destroyed. Mass can only be transformed from one form to another. The law of conservation of mass was given by Antoine Lavoisier.

Every reaction in nature follow the law given by Antoine Lavoisier that is mass is always conserved. Another postulated that was given by Antoine Lavoisier is the role of oxygen in combustion reaction.  total mass of reactant must be equal to total mass of product.

Therefore, the total mass of reactant must be equal to total mass of product.

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When 6.2 moles of propane is burned in oxygen, it produces approximately 818.4 g of carbon dioxide.

Here, stoichiometry (a branch of Chemistry) is used to determine the product generated from a known quantity of reactants. The balanced equation for the combustion of propane is C3H8 + 5O2 → 3CO2 + 4H2O. This shows that 1 mole of propane (C3H8) produces 3 moles of carbon dioxide (CO2). So, it's a 1:3 ratio. Given that the molar mass of CO2 is approximately 44 g/mol, you can first find how many moles of CO2 are produced by multiplying the given moles of propane by 3 (6.2 × 3 = 18.6 moles CO2). Then, determine the mass by multiplying the moles of CO2 by the molar mass of CO2 (18.6 × 44 = 818.4 g). Thus, the combustion of 6.2 moles of propane yields 818.4 g of carbon dioxide.

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Answer:

cells; energy

Explanation:

Answer:

All organisms are made up of cells, the basic unit of structure and function. Homeostasis is the ability to do work and allows living things to perform all the functions necessary to live.

Explanation:

Cells are the building blocks of all life and make up the structure and allow an organism to function properly. Homeostasis defines the second term. Hope this helps, have a great one!

Answer:

D

Explanation:

As you move down anything, towards the earth, (gravitational) potential energy decreases. This eliminates options B and C.

By the law of conservation of energy, the energy of the system stays the same. However the energy may be converted into different forms. In this case, the potential energy is converted into kinetic energy - this is what makes people move faster as they go down the slope. This makes option A wrong and option D right.

Answer: The answer is C

Explanation:

Answer:

H + ions are attracted to the cathode , gain electrons and form hydrogen gas. OH - ions are attracted to the anode , lose electrons and form oxygen gas.

Answer:

transition elements

Explanation:

Metalloids are elements that have properties intermediate between those of metals and nonmetals. They are sometimes referred to as semi-metals. These materials have recently found great application in materials science and information technology.

Transition elements are however renowned for high densities and tensile strength. The transition elements have the highest density of all the element groups in the periodic table and also have resistance to corrosion. Transition metals such as gold silver and lead are coinage metals because they are resistant to corrosion.

Alkali and alkaline earth metals tarnish easily due to their high reactivity. They are usually very soft metals.

Answer:

Transition elements

Explanation:

Transition elements occupies the middle section of the periodic table. Generally, transition elements are metallic in nature. Examples of transition elements are scandium, titanium , vanadium, copper, cobalt, zinc , chromium, manganese , iron etc. Since transition elements are all metallic they are hard , lustrous , are good conductor of electricity and heat and have a high melting and boiling points .

Transition metals are also used as catalyst in many reactions. Transition metals have high densities compare to alkali and alkali earth metals. Transition element are less reactive compare to other metallic elements like the alkali and alkaline earth metals .

Transition metals are usually less reactive and they rarely react with oxygen in air . This resistance account for it noncorrosive nature. Example of this noncorrosive transition metals are silver, Titanium, chromium, manganese, copper etc .

Alkali and alkali earth metals are very reactive so they are likely corrosive. Metalloids don't have high densities and strength.    

3.75 litres is the volume of the balloon indoors at a temperature of 25°C.

Explanation:

Data given:

initial temperature of the gas in balloon  = -35°C or 238.15 K

initial volume = 3 litres

final temperature = 25 °C  or 298.15 K

final volume =?

pressure remains constant

From the data given when pressure is constant Charles' law is applied.

[tex]\frac{V1}{T1}[/tex] = [tex]\frac{V2}{T2}[/tex]

Rearranging the equation to know the final volume of the gas in balloon

V2 = [tex]\frac{V1T2}{T1}[/tex]

V2 = [tex]\frac{3 X 298.15}{238.15}[/tex]

V2 = 3.75 Litres

when the temperature of a gas is increased and pressure remains constant the volume of the gas increases.

The Volume of the balloon indoors in increased by 3.8 L.

Explanation:

As per the Charles law, at constant pressure the volume of the gas is in direct proportion with the temperature measured in Kelvin. As temperature increases, the volume expands that is increases and vice-versa.

[tex]$\frac{V1}{T1} = \frac{V2}{T2}[/tex]

T1 = -35° C + 273 K = 238 K

T2 = 25° C +  273 K = 298 K

V1 and T1 are the Volume and the temperature of the balloon inflated outdoors.

V2 and T2 are the Volume and the temperature of the balloon inflated indoors.

V2 can be found by rearranging the above equation as,

[tex]$V2 = \frac{V1 T2}{T1}\\[/tex]

[tex]$V2 = \frac{3 L \times 298 K}{238 K}[/tex]

    = 3.8 L

So the Volume of the balloon indoors in increased by 3.8 L.

Answer:

I beleive its diesel engines

Explanation:

Burning of wood is a combustion reaction and the metabolism of glucose in your cells is cellular respiratory reaction.

Cellular respiration releases stored energy in glucose molecules and converts it into a form of energy that can be used by cells.

Cellular respiration is the process by which organisms combine oxygen with foodstuff molecules, diverting the chemical energy in these substances into life-sustaining activities and discarding, as waste products, carbon dioxide and water.

Wood as well as many common items that combust are organic (i.e., they are made up of carbon, hydrogen and oxygen). When organic molecules combust the reaction products are carbon dioxide and water (as well as heat)

Similarities:

1. Combustion reaction and metabolism of glucose both require oxygen.

2. Combustion and metabolism of glucose both product carbon dioxide and water

3. Both produces by-products: After cellular respiration and combustion have gotten what they needed from the wood, there will be byproducts from the conversion. In the case of combustion, they are noxious gases like carbon monoxide. In the case of respiration, the sugar molecule is broken into two molecules of pyruvic acid.

4. Catalyst: While breaking apart the bonds to release the stored energy either combustion or sugars for respiration the bonds will not broken by themselves. In each case, a catalyst is required to start the reaction that will break the bonds apart. In the case of combustion, the catalyst is a spark. Wood are flammable, so the spark will ignite the burning, breaking apart the bonds and releasing the energy. For respiration, enzymes are used to break the sugar molecule apart.

Differences

1. Glucose metabolism produces a chemical energy, while combustion produces light and heat energy.

2. Glucose metabolism is an endothermic reaction while combustion is an exothermic reaction (produces heat)

Answer:

a dozen eggs is 12 eggs. Three dozen is 36 eggs. so no

Explanation:

Final answer:

To find the number of grams of magnesium in 7.43×10²² atoms, convert the number of atoms to moles and then to grams using the molar mass of magnesium.

Explanation:

To calculate how many grams of magnesium are in 7.43×10²² atoms of Mg, you need to convert the number of atoms to moles and then to grams. The molar mass of magnesium is 24.30 g/mol, which means that one mole of magnesium atoms weighs 24.30 grams.

First, calculate the number of moles of magnesium using the Avogadro's number and the given number of atoms: (7.43×10²² atoms) / (6.02×10²³ atoms/mol) = 0.123 moles of Mg.

Next, multiply the number of moles by the molar mass to get the grams of magnesium: 0.123 moles × 24.30 g/mol = 2.992 grams of Mg.

Answer : The correct option is, (4) 6.0 mol

Explanation :

The given balanced chemical equation is,

[tex]3Pb^{2+}+2Cr\rightarrow 3Pb+2Cr^{3+}[/tex]

In this reaction, lead undergoes reduction and chromium undergoes oxidation.

Oxidation reaction : It is the reaction in which a substance looses its electrons. In this oxidation state increases.

Reduction reaction : It is the reaction in which a substance gains electrons. In this oxidation state decreases.

Half reactions of oxidation-reduction are :

Oxidation : [tex]2Cr\rightarrow 2Cr^{3+}+6e^-[/tex]

Reduction : [tex]3Pb^{2+}+6e^-\rightarrow 3Pb[/tex]

From the reduction reaction, we conclude that 6 moles of electrons gained by the 3 moles of lead ions.

Hence, the correct option is, (4) 6.0 mole

Answer:

I believe it goes to the left

Explanation:

GOOGLE it or ask me for more questions :)

Answer:

Answer: C) Geothermal energy requires high subsurface temperatures that can be found west of the Mississippi River.

Explanation: i took the usa test prep and got it right!!