Chemistry Middle School
Answers
Answer 1
Answer:
It is a. Chemical reaction that happens.
Explanation:
Answer 2
Answer:
Chemical reaction
Explanation:
Related Questions
What’s a crystallisation
Answers
Answer:
passage of water at 0 degrees
Crystallization is the solidification of atoms or molecules into a highly structured form called a crystal.
Explain how density affect boiling point
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Answer:
A liquid boils at a temperature at which its vapor pressure is equal to the pressure of the gas above it. The lower the pressure of a gas above a liquid, the lower the temperature at which the liquid will boil
Explanation: Factors That Affect the Boiling Point
Pressure: when the external pressure is:
less than one atmosphere, the boiling point of the liquid is lower than its normal boiling point.
equal to one atmosphere, the boiling point of a liquid is called the normal boiling point.
greater than one atmosphere, the boiling point of the liquid is greater than its normal boiling point.
The following graph shows the boiling point for water as a function of the external pressure. The line on the graph shows the normal boiling point for water.
Blood makes up about what percent of our body mass?
Answers
Answer:
7%
Explanation:
The amount of blood in the human body is generally equivalent to 7 percent of body weight. #answerwithquality #BAL
Answer:
7.8% of body weight
Explanation:
blood in human is 7.8% of body weight
Reason why chemistry is studied
Answers
Answer: Chemistry is the study of change. Various reasons why to study Chemistry is to appreciate the fundamentals of the world such as the composition of all living thing. We are made up of matter. The interaction of sub atomic particles in an atom to form a single being. Also to understand how certain chemicals are beneficial and harmful in our lives just by reading product labels.
Explanation:
(I have a chemistry study guide that confuses me, anything will help!!!) 1) The variable observed during an experiment
is called
2) Pure Chemistry is defined as
3) If the given mass of silver is 45.6g , and the density of silver is 10.5g/ml, calculate the volume
4) An example of physical properties of a substance is
5) Difference between a mixture and a compound is
6) Particles found in nucleus are
7) The sum of the protons and neutrons in an atom equals the
8) The maximum number of d orbitals in a principal energy level are
9) Elements that are characterized by the filling of p orbitals are classified as
10) The atomic radius ------------- ( increase/decrease) from top to bottom in a group in the periodic table
11) Cations are formed by
12) Compared with the electronegativities of the elements on the left side of a period, the electronegativities of the elements on the right side of the same period tend to be ____(lower/higher)
13) The number of valence electrons are in a silicon atom are
14) The formula for sodium sulfate
15) The characteristic of metals that makes them good electrical conductors
16) The weakest attraction between molecules is called
17) The formula of phosphoric acid is
18) the correct name for CoCl2 is
19) The empirical formula of a substance that is 53.5% C, 15.5% H, and 31.1% N by weight is
20) The percent composition of chromium in BaCrO4
Answer the following in full sentences; Show your complete work for numerical problems
1) The element chromium has four naturally occurring isotopes. Use the relative abundance of each to calculate the average atomic mass of chromium.
Cr=4.34%, Cr=83.79%, Cr=9.50% and Cr=2.37%
2) Write down the electron configuration for the chloride ion and sulfide ion
3) Calculate the percent by mass of hydrogen in aspirin, C9H8O4
4) Describe the shapes and relative energies of the s, p, d, and f atomic orbitals
5) Explain how atoms (ions) are held together in an ionic bond. Give an example of an ionic compound
6) A 500-g sample of Al2 (SO4)3 is reacted with 450 g of Ca (OH)2. A total of 596 g of CaSO4 is produced. What is the limiting reagent in this reaction, and how many moles of excess reagent are unreacted? ( Full credit will be given for this question as this topic was skipped)
7) Predict the precipitate that forms when aqueous solutions of silver nitrate and potassium chloride react to form products in a double-replacement reaction. Include a discussion of how to write the complete chemical equation describing this reaction.
8) Compare and contrast Dalton’s atomic theory with JJ Thompson’s Plum pudding model.
9) How many liters of O2 are needed to react completely with 45.0 L of H2S at STP?
10) The diameter of a carbon atom is 0.000000000154 m. What is this number expressed in scientific notation?
11) Explain what is meant by VSEPR theory. Give an example of how VSEPR theory can be applied to predict the shape of a molecule.
12) What is the quantum mechanical model?
Answers
Answer:
1) Dependent Variable
3)4.34cm cubed
5)Compound contains atoms which are chemically bonded. Mixture contains random arrangement of elements.
6)Protons, neutrons
7)Atomic Mass
10) increases
13)4 electrons
14) Na2SO4
15)Delocalize electrons
16) Van Der Waal forces
17)H3PO4
18) Cobalt(||) Chloride
This is the most I got. Tell me if u want more.
:)
Variable observed in experiment is independent variable for question 1!
Why does H2O have a lower melting point than MgO
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Answer:
Magnesium Oxide (MgO) has a higher melting point than Sodium Chloride (NaCl) which is around 2,800 degrees Celcius. This is because its Mg2+ and O2- ions have a greater number of charges, and so form stronger ionic bonds, than the Na+ and Cl– ions in Sodium Chloride.
A and B are powders, A is insoluble while B dissolves to give a pH 3 solution. Mixing A and B gives bubbles or effervescence and a clear solution. a) which is the acid?
b) if the other substance is a carbonate, name the gas given off.
c) even though A is insoluble a clear solution is given off, explain why.
Answers
Answer:
a) B is an acid
b)carbon dioxide
c) it is salt of the acid
Explanation:
a) B dissolves to produce an acid. An acid, according to the Bronsted-Lowry theory, dissolves in an solution to give an acid solution of a pH less than 7 on a pH scale.
b) carbonates gives a gaseous effervescence. The gas given off is carbon dioxide
c) The solution is a salt of an acid. This is in an aqueous solution.
Answer:
I think it is a nitric acid
Calculate the pH of a solution formed by mixing 20.00 mL of 0.30 M HCl with 30.00 mL of 0.15 M HNO3??
Answers
Answer:
0.68
Explanation:
Both and are strong acids which ionize completely in water. According to stoichiometry, 1 mole of each will produce 1 mole of hydronium cations. Therefore, let's calculate the total number of moles of hydronium and find the final concentration of it keeping in mind the dilution:
Total molarity:
Find pH:
Micah is investigating the transformation between potential and kinetic energy within a system. He uses a swinging pendulum in his investigation. He records his observations of the pendulum at different positions and creates the table below. KINETIC AND POTENTIAL ENERGY OF A PENDULUM
Position Kinetic Energy (Joules) Potential Energy (Joules)
1 0 50
2 25 25
3 50 0
4 25 25
5 0 50
Which statement BEST describes the energy transformation in Michah's investigation?
The total energy of the system is maintained as energy is transformed.
The total energy of the system increases as kinetic energy is created.
The total energy of the system decreases as potential energy is destroyed.
The total energy of the system changes as energy is added to it.
Answers
The total energy is maintained as energy is transformed because the law of Conservation of Energy states that energy is not created or destroyed, just transformed from one form to another
What are properties that metals all have? I need 3
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Answer: Metals are good conductors of heat and electricity, Malleability and all are solid in room temperature except for Mercury (Hg)
Explanation:
Answer:
solid at room temperature (with the exception of mercury)
usually shiny.
high melting point.
good conductor of heat.
good conductor of electricity.
low ionization energies.
low electronegativities.
malleable – able to be pounded into sheets.
Explanation:
Micah is investigating the transformation between potential and kinetic energy within a system. He uses a swinging pendulum in his investigation. He records his observations of the pendulum at different positions and creates the table below. KINETIC AND POTENTIAL ENERGY OF A PENDULUM
Position Kinetic Energy (Joules) Potential Energy (Joules)
1 0 50
2 25 25
3 50 0
4 25 25
5 0 50
Which statement BEST describes the energy transformation in Michah's investigation?
The total energy of the system is maintained as energy is transformed.
The total energy of the system increases as kinetic energy is created.
The total energy of the system decreases as potential energy is destroyed.
The total energy of the system changes as energy is added to it.
Answers
Answer: The total energy is maintained as energy transformed
Explanation:
The kinetic energy and potential energy is been maintained as each of the experiment is been performed which is 50Joules
Answer: the total energy is maintained as the energy transformed. Good luck
Explanation:
What is the scientific method? O
A. An organized way to test scientific ideas
O
B. A formula for analyzing scientific data
O
C. A plan for forming a scientific hypothesis
D. A technique for testing a scientific theory
Answers
Answer:
An organized way to test scientific ideas
Explanation:
Just did the test xx
Determine if these molecules and ion are polar. Explain your answers.
a. H3O+
c. H2s
b. PCI5
d. CF4
Answers
A) H₃O⁺ : Polar
B) H₂S : Polar
C) PCI₅ : Non-polar
D) CF₄ : Non-polar
Polar molecules are molecules with a net dipole ( i.e. They are partially positive and partially negative ).
H₃O⁺ is a polar ion with a net charge as it contains a positive charge.
H₂S is a polar molecule because of the presence of two lone pairs of sulfur atoms and it has a bent structure just like water making it a polar molecule.
PCI₅ is a nonpolar molecule because the central atom ( P ) does not contain lone pairs of electrons.
CF₄ is a nonpolar molecule because it has tetrahedral geometry and does not have lone pairs on carbon atom.
Hence we can conclude the molecules and ion listed above are ; a) Polar, b) Polar, c) Non-polar and d) Non-polar
Learn more : brainly.com/question/17939593
Answer:
a. Polar
b. Polar
c. Non-polar
d. Non-polar
Explanation:
a. , hydronium cation contains a positive charge. Just as any other ion, it is polar, as it has a net charge.
b. has the same shape as water. There are two lone pairs on sulfur atom which produce an overall dipole moment in this molecule, the bent structure is polar.
c. is non-polar, as the central atom, phosphorus, doesn't contain any lone pairs, all the dipole moments cancel out: two dipole moments in the vertical plane, P-Cl, and three P-Cl dipoles in the horizontal plane within a trigonal bipyramidal shape.
d. is non-polar, since it's a tetrahedral molecule with no lone pairs on carbon atom, all four C-F dipole moments cancel out to yield a net 0 dipole moment.
Ionization changes identity of substance?
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Answer:yes because due to ionization atom makes chemical bonds with other atoms, which makes change in the properties of atoms
Explanation:
What is the voltage of a galvanic cell made with magnesium and gold
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The voltage of a galvanic cell made with magnesium and gold is 4.2 V
Balance the chemical equation Na3PO4(aq)+NiCl2(aq)—>Ni3(PO4)2(s)+NaCl(aq)
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Answer: 2 Na3PO4 + 3 NiCl2 ---> Ni3(PO4)2 + 6 NaCl
Explanation: to balance this chemical equation inspect first Na and Ni in both the reacant and product side. Balance each elements by writing 2 on Na3PO4 so sodium will have 6 atoms on the reactant side. on the product write 6 on NaCl. Put 3 on NiCl2 to balance Nickel and Chlorine atoms. Na have 6 atoms in both reactant and product, P have 2 atoms both, O has 8, Ni has 3 atoms and Cl has 6 atoms in both sides. So the equation is now balanced.
Answer:
2Na3PO4 + 3NiCl2 --> Ni3(PO4)2 + 6NaCl
Explanation:
Balancing the Na3PO4 first then the NaCl and finally the NiCl2
Convert 9.97x10^19 molecules NH3 to moles
Answers
Answer: 1.66x10 +4 moles of NH3
Explanation: To find the number of moles just divide the given value of molecules to the Avogadro's number.
Solution: 9.97x10 +19 molecules NH3 X 1 mole NH3 / 6.022X10+23
Answer:
604.11
Explanation:
1 mole = 6.023 × 10^23 (avogadros constant)
6.023 × 10^23 ÷ 9.97 × 10^19
How do the Earth, the moon and the sun interact?
Answers
Earth orbits around the sun and the moon orbits around earth, the sun provides us heat and light and the sun beams at night reflect of the moon like a mirror causing light each one has a gravitational pull
Answer:
the sun helps the earth and the moon helps the earth as well
This is the chemical formula for talc (the main ingredient in talcum powder): Mg3( Si2O5)2(OH)2
An analytical chemist has determined by measurements that there are 21.4 moles of magnesium in a sample of talc. How many moles of silicon are in the sample?
Answers
Answer:
28.53 moles of silicon
Explanation:
Chemical formula helps us to see which elements are contained in a compound. If correctly written, it can also help us see how much atoms of each element are there.
For this particular case, in one molecule of talc, we have;
3 atoms of Mg
4 atoms of Si
12 atoms of O
2 atoms of H
From here, we can find the ratio of any two atoms from the molecule. So, we can say that the ratio of Mg: H is 3:2, or that ratio of O: Mg is 12:3 etc.
Now, if we expand this concept on moles, we can easily solve this problem.
We know there are 21.4 moles of Mg and want to know how many moles of Si are there. Since we can see the ratio of Mg: Si which is 3:4, we write a proportion:
3 : 4 = 21.4 : x
x = 21.4 • 4 / 3
x = 28.53 moles of Si
Are ionic bonds more powerful or colvant? And why do molecular compounds not have crystal lattice?
Answers
Answer:
Ionic bonds are more powerful than covalant bonds
Explanation:
This is because of their strong lattice structure formed by the attraction between metals and non-merals.
Molecules donot exhibit crystal lattices because of the covslent bonds present in between their molecules