Sắt oxit
Explanation:
Which is true of the enthalpy of a reaction?
A. Its value depends on which reactions are added
B. Its value is the same as the enthalpy of each intermediate reaction
c. Its value is always a negative kJ/mol
D. Its value does not depend on which reactions are added
D. It’s value does not depend on which reactions are added
PLEASE HELP ME!
When magnesium powder is heated, it combines with oxygen to form white magnesium oxide powder.
(a) State one use of magnesium oxide.
(b) Write the chemical equation of this reaction.
(c) Calculate the mass of magnesium oxide formed if 3g magnesium is completely burnt in excess oxygen.
(d) The magnesium oxide is basic and reacts with hydrochloric acid to form magnesium chloride salt and water. Write the chemical equation of this reaction. (Relative atomic mass of O=16,Mg=24)
Explanation:
a. Magnesium oxide is used mainly in soil treatment and groundwater remediation, wastewater treatment, etc. it is used for it's acid buffering capacity and effectiveness in dissolving heavy metals.
b. MgO is the chemical equation for the reaction.
c. multiply the given mass of O2 by the inverse of it's molar mass. multiply the molar ratio (from the balanced equation) between O2 and MgO. Multiply by the molar mass of MgO. 32g O2 x 1 mol O2 ... 32g O2 x 2mol MgO 1mol O2 x 40g MgO. .... 1mol MgO = 80 g.
d. Mg (s) + 2 HCl (aq) produces MgCl 2(aq) + H 2 (g). Where the letter "s" stands for solids, and "g" is for gas and "aq" represents aqueous solution.
Explain a polar molecules and give examples
What will change if liquid 5.0 molar NiCl2 is added?
When liquid 5.0 molar NiCl₂ is added to 0.3 M of NiCl₂ solution :
Molarity will increase ( A )
What is Molarity ?
Molarity is the measure of the number of moles of solute present per volume of the solution. The addition of 5.0 molar nickel chloride into a 0.3M Nickel chloride solution will lead to an increase in the number of moles of Nickel chloride present in the solution.
Molarity is directly proportional to moles of solute in a solution therefore the molarity of the solution will increase.
Hence we can conclude that When liquid 5.0 molar NiCl₂ is added to 0.3 M of NiCl₂ solution : Molarity will increase.
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7th grade science help me plsssss
1. Organism: (description) an individual animal, plant, or single-celled life form.
(example) Humans, squids, mushrooms, and vascular plants
2. Population: (description) A population is all the inhabitants of a particular
place
(example) All institutionalized elderly with Alzheimer's
All people with AIDS
3. Community: (description) A community is a social unit with commonality such as norms, religion, values, customs, or identity. Communities may share a sense of place situated in a given geographical area or in virtual space through communication platforms.
(example) a forest of trees and undergrowth plants, inhabited by animals and rooted in soil containing bacteria and fungi
4. Ecosystem: (description) An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system.
(example) agroecosystem, aquatic ecosystem, coral reef etc.
5. Biosphere: (description) The biosphere is the worldwide sum of all ecosystem
(example) An example of the biosphere is where live occurs on, above and below the surface of Earth.
mark me brainliestttt :)))
Help I dont know how to do this
How many bonds can a hydrogen atom form?
O A. 3
O B. 1
O c. 4
O D. 2
Answer:
the right answer is b !!!
Which substance would require the most energy to heat 10.00 g of it by 10.0°C?
O Ice, c = 2.03 Jigº
O Mercury, c = 0.140 J/gºC
O Water, c = 4.18 J/gºC
O Aluminum, c = 0.902 J/gºC
Answer:
a
Explanation:
a
Which of the following is the correct electron
configuration for titanium (Ti)?
Answer:
1s2 2s2 2p6 3s2 3p6 4s2 3d2
Explanation:
1s2 2s2 2p6 3s2 3p6 4s2 3d2
Which number is equal to the number of protons in the atom
Answer:
The number of electrons is equal to the number of protons
To see the number of atoms of an element in a given molecule we need to multiply stoichiometry to the number that is written on the foot of the element that is stoichiometry. Therefore, the electrons number is equal to the number of protons in the atom.
What is atom?Atom is the smallest particle of any element, molecule or compound. Atom can not be further divided. Atoms contains nucleus in its center and electron that revolve around the atom in fixed orbit.
In the nucleus, proton and neutron are present. Electron has -1 charge while proton has +1 charge. Neutron is neutral that is it has no charge. So overall the charge of nucleus is due to only proton, not by neutron. In an atom, the number of electron or atomic number is s equal to the number of protons in the atom.
Therefore, the electrons number is equal to the number of protons in the atom.
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8. Why do we see water droplets on the outer surface of a glass containing ice cold water?
9. Convert the following temperature to the CELCIUS scale (a) 25K (b) 373K.
10. How will you show that air has maximum compressibility?
Answer:
8. We see water droplets on the outer surface of a glass containing ice cold water because condensation is happening! This happens when warm water vapour from the surroundings come into contact with a cool surface (in this case the cool glass) and loses heat and condenses, forming water droplets on the surface of the glass.
9 a) -248.15 celcius
b) 99.85 celcius
10. by using 2 syringes, one filled with water and one filled with air. when you compress it, you will find that the one with water barely compresses and the one filled with air should be able to be compressed quite a bit. and to the extent that the syringe is unable to be pushed down further, that is the maximum compressibility of air.
Which force holds the nucleus of an atom together?
A. Strong nuclear force
B. Weak nuclear force
C. Electrostatic force
D. Gravity
Answer:
Strong nuclear force
The lab question is "Based on a substance's properties, how can you determine whether it's bonds are ionic or covalent?" Fill in the bot to answer this question with a hypothesis Hypothesis: if a substance contains ionic bonds, then it's properties would include…
Answer:
Through its features.
Explanation:
If a substance contains ionic bonds, then it's properties would include high melting and boiling point, form crystals, hard and good conductors of and electricity while on the other hand, if a substance contains covalent bonds, then it's properties would include soft structure, low melting and boiling points, did not form crystals and poor conductor of heat and electricity so we can conclude that properties of covalent and ionic compounds helps in determining the bonds exists between them.
Sample hypothesis: If a substance is solid at room temperature, has a crystalline structure, dissolves easily in water, and conducts electricity well, then it likely contains ionic bonds.
7) The negative-feedback system of the endocrine system works much like a ______
Answer: Most of the hormones released by endocrine system are regulated by negative feedback mechanism.
- Negative feedback mechanism functions to reduce the intensity of original stimulus in order to maintain homeostasis.
Explanation:
When blood calcium levels are decreased, parathyroid gland releases parathyroid hormone (PTH).
PTH acts on bone and stimulate bone resorption by promoting osteoclastic activity. It stimulates reabsorption of calcium in kidneys. PTH promotes calcitriol synthesis that acts on small intestine to increase calcium absorption.
Action of PTH increases blood calcium levels.
When blood calcium levels are increased, thyroid gland releases hormone calcitonin.
Calcitonin opposes PTH and acts to deposit calcium in the bone.
Calcitonin acts on osteoblasts and promote increase in bone mass.
Action of calcitonin decreases blood calcium levels.
Which three types of reactions yield a product that is a chemically bonded combination of reactants?
Answer:
oxidation, synthesis, polymerization.
A cup of coffee has 71 mL of coffee and 127 mL of water. What is the
percent by volume of the coffee solution? *
Answer:
[tex]total \: volume = 71 + 127 \\ = 198 \: ml \\ \% \: coffee = \frac{71}{198} \times 100\% \\ = 35.86\%[/tex]
How many moles is 6.88 x 10^-2 g silver chloride ?
Answer:hey
Explanation:
Đốt cháy hoàn toàn 0,1 mol axit đơn chức cần V lít O2 ở đktc. Thu được 0,3 mol CO2 và 0,2 mol h20 vậy giá trị V là
Answer:
Complete combustion of 0.1mol of monocarboxylic acid requires V litres of O2 at dtc. and the reaction produces 0.3mol of CO2 and 0.2mol of H2O.
What is the value of V?
Explanation:
The balanced chemical equation of the reaction is
[tex]HCOOH+O_2 -> 2CO_2+2H_2O\\[/tex]
1mol. of acid reacts with 1mol of [tex]O_2[/tex] and produce 2mol. of CO2 and 2mol. of H2O.
Given,
0.1mol of acid requires how many litres of oxygen at STP?
0.1mol of acid requires 0.1mol of oxygen.
Since, 1mol of oxygen at STP occupies 22.4L of volume.
Hence, the volume occupied by 0.1mol of oxygen is -- 2.24L
Answer is:
The value of V is 2.24L.
The closest living relatives to Gorillas are:
(Look at pic)
A. Humans
B. Chimpanzees, and humans equally
C. Orangutans
D. Chimpanzees
(DO NOT ANSWER IF YOU CANNOT ACTUALLY HELP)
magnesium hydroxide + sulfuric acid please
Answer:
H2SO4 + Mg(OH)2 → H2O + MgSO4
Explanation:
when magnesium hydroxide reacts with sulfuric acid you get magnesium sulfate
hope this helps
[tex]what \: is \: chemical \: reaction \: {?} \: [/tex]
what is a chemical reaction?
Explanation:A chemical reaction is a process in which one or more reactants are transformed into one or more products. Chemical elements and compounds are both substances. The component atoms of the reactants are rearranged in a chemical reaction, resulting in distinct compounds as products.
-------------------------hope it helps...have a great day!!Which statement best supported by the data on the map
The correct pathway for air entering the human respiratory system is _______.
A)nose, trachea, alveoli, bronchi
B)nose, bronchi, trachea, alveoli
C)alveoli, trachea, epiglottis, nose
D)nose, trachea, bronchi, alveoli
Answer: D
Explanation:
This cell is dividing into two cells.
Answer:
answer: B or D
Explanation:
hope it helps thanks❤
4. If the relative molecular mass of CH20 is 60.
calculate its empirical formula. (C = 12. H = 1
0 = 16)
A 4
В І
C2
D 3
Answer:
C2H4O2
Explanation:
because you do mr of CH2O= 12+2+16=30
so 60÷30=2 empirical units
so CH2O × 2=C2H4O2
hope this helps :)
The Empirical formula of the given compound is CH₂O
What is Empirical formula ?A formula giving the proportions of the elements present in a compound but not the actual numbers or arrangement of atoms.
Empirical formula mass = 12g/mol + 2 g/mol + 16 g/mol = 30 g/mol
Molecular formula mass / Empirical formula mass = 60 g/mol / 30 g/mol
= 2
Molecular formula = 2 × CH₂O = C₂H₄O₂
Empirical formula = CH₂O
Empirical formula mass = 12g/mol + 2 g/mol + 16 g/mol = 30 g/mol
Therefore, The Empirical formula of the given compound is CH₂O
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The emission spectrum of hydrogen is shown below. What do the lines in the
spectrum show?
A. Light with wavelengths between 410 nm to 434 nm, 434 to 486 nm, and 486 to 656 nm corresponds with the three energy levels in
hydrogen
B. Only light with wavelengths of 410 nm, 434 nm, 486 nm, and 656 nm is not taken in during energy transitions.
C. Light with wavelengths of 410 nm, 434 nm, 486 nm, and 656 no corresponds with the four energy levels in hydrogen.
D. Light with wavelengths of 410 nm, 434 nm, 486 nm, and 656 nm is given off when electrons fall to lower energy levels.
Answer:
A
Explanation:
Same air has special carakteristik features
PLEASE HURRY!
What is the half-life of a 12 g sample of radioisotope that decayed to 6 g in 28
years?
A. 14 years
B. 7 years
C. 56 years
D. 28 years
Answer:
28 years
Explanation:
the information is literally in the question.
Which of the following issues surrounding nuclear power creates the biggest
concern?
A. Where nuclear power should be used
B. How to deal with the radioactive waste
c. How many power plants should be built
O D. What nuclear power should be used for
Question : Which issue surrounding nuclear power creates the biggest concern?
Answer : How to deal with the radioactive waste (B)
The following issues surrounding nuclear power that create the biggest concern is What nuclear power should be used for?
What is nuclear power?Nuclear powers are those powers that are produced by nuclear reactions. These reactions include nuclear fission, nuclear fusion, and nuclear decay. Nuclear power is currently in use to produce electricity. The reaction uses uranium and plutonium reaction to produce electricity.
Nuclear power is used for generating electricity, and it is necessary to use the correct radioisotopes to produce electricity.
Thus, the correct option is D. What nuclear power should be used for?
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Plz HElp!!!!
3 The density of water is 1 g/cmº. A substance will float if its density is less 33 points
than that of water. Which of the following substances will float?*
Substance
Mass
Volume
1
69
3 cm3
2
89
4 cm3
3
109
2 cm3
4
29
4 cm3
O Substance 1
O Substance 2
Substance 3
O Substance 4
Answer:
Substance 4
Explanation:
Density is defined as mass per unit volume. A substance floats in another when its density is less than that of the substance on which it floats.
If an object is immersed in a denser liquid, it will sink
Since the density of water is 1 g/cm^3, any substance whose density is less than that of water will float in it.
If we look at the table, substance 4 has a density of 0.5g/cm^3. Hence, substance 4 is expected to float in water.
What is the Net Ionic equation for this chemical reaction: FeBr2+Na2S=FeS+2NaBr
Answer: Fe(aq)+S(aq)=FeS(s)
Explanation: The Sodium and Bromine are spectator ions because they don't react with anything, you can see this by writing the ionic equation like so:
1.) Molecular formula (given): FeBr2 (aq)+Na2S (aq)= FeS(s)+2NaBr(aq)
Each dissolved FeBr2 breaks up into one Fe with a charge of 2+ and two Br with a negative charge. This gives you:
Fe(aq)+ 2Br(aq)+Na2S(aq)=FeS(s)+2NaBr
2.) Now repeat what was shown with the other compounds in the given molecular formula, and pay attention to the states that each ion is in (solid, liquid, aqueous, gas) because this will give you the ionic equation, which from there you can get rid of any ions that don't change amount or state.
3.) Ionic formula: Fe(aq)+ 2Br(aq)+2 Na(aq)+S (aq)=FeS(s)+2 Na(aq)+2Br(aq)
4.)When you've derived a total ionic equation (above), you'll find that some ions appear on both sides of the equation in equal numbers. For example, in this case two Na cations and two Br anions appear on both sides of the total ionic equation. What does this mean? It means these ions don't participate in the chemical reaction. They're present before and after the reaction. Nothing happens to them. So those are removed and you're left with the net ionic: Fe(aq)+S(aq)=FeS(s)
Hope this helps :)
