A chemist wants to calculate the amount of heat that is absorbed by a sample of copper as it is melted. Which constant should she use?
Answers
I hope his helps. Let me know in the comments if anything is unclear.
Answer:
Hfus
Explanation:
This is correct on edge.
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Answers
and another name :
In this case, no amount of oxidant, i.e. oxygen enough to burn all the fuel.
hope this helps!
b. decrease in the number of neutrons in the nucleus of an atom
c. increase in the number of neutrons in the nucleus of an atom
d. change in the number of protons in a nucleus of an atom
Answers
Answer: Option (d) is the correct answer.
Explanation:
Transmutation is a process which brings changes in the nucleus occur because of change in the number of protons of an atom. Therefore, the atom formed will have different properties from its parent atom.
For example,
A transmutation can be natural or artificial in nature.
Thus, we can conclude that a transmutation reaction must always involve a change in the number of protons in a nucleus of an atom.
Answers
Given:
1,500 mL of water
1.33 m (molal solution
Required:
grams of hydrogen peroxide (H2O2
solution:
1.33 molal = 1.33 m = 1.33 moles H2O2/kg water
1 gram/liter of water (1 liter/1000 mL) (1500mL)(1 kg/1000g) = 0.0015 kg water
1.33 moles H2O2/kg water (0.0015 kg water) = 0.001995 moles H2O2
Molar mass of H2O2 = 34 g/mol
0.001995 moles H2O2 (34 g/mol) = 0.068 grams H2O2
a. True
b. False
Answers
3. Two factors that determine whether a molecule is polar are the types of atoms in the molecule and the ____________________ of the molecule.
4. According to John Dalton’s observations, when elements combine in a compound
A. The ratio of their masses is always the same.
B. Each element contributes an equal number of atoms.
C. Their volumes are always equal.
D. Their masses are always equal.
5. Democritus thought that matter was made of tiny particles
A. Of earth, air, fire, and water.
B. That could not be divided.
C. That could be divided.
D. That were all round and smooth
6. Rutherford’s gold foil experiment provided evidence for which of the following statements?
A. Negative and positive charges are spread evenly throughout an atom.
B. Alpha particles have a positive charge.
C. Gold is not as dense as previously thought.
D. There is a dense, positively charged mass in the center of an atom.
7. Which statement about subatomic particles is true?
A. Protons, neutrons, and electrons all have about the same mass.
B. Unlike protons or neutrons, electrons have no mass.
C. Neutrons have no charge and no mass.
D. An electron has far less mass than either a proton or neutron.
8. Which statement is true about oxygen-17 and oxygen-18?
A. They do not have the same number of protons.
B. Their atoms have an identical mass.
C. They are isotopes of oxygen.
D. They have the same mass number.
9. Which statement accurately represents the arrangement of electrons in Bohr’s atomic model?
A. Electrons vibrate in fixed locations around the nucleus.
B. Electrons travel around the nucleus in fixed energy levels with energies that vary from level to level.
C. Electrons travel around the nucleus in fixed energy levels with equal amounts of energy.
D. Electrons travel randomly in the relatively large space outside the nucleus.
10. What does the electron cloud model describe?
A. The most likely locations of electrons in atoms
B. The precise locations of electrons in atoms
C. The number of electrons in an atom
D. The mass of the electrons in an atom
11. What is the difference between an atom in the ground state and an atom in an excited state?
A. The atom in the ground state has less energy and is less stable than the atom in an excited state.
B. The atom in an excited state has one fewer electron than the atom in the ground state.
C. The atom in an excited state has more energy and is less stable than the atom in the ground state.
D. The atom in an excited state has one more electron than the atom in the ground state.
12. The usefulness of Mendeleev’s periodic table was confirmed by
A. the discovery of subatomic particles.
B. its immediate acceptance by other scientists.
C. the discovery of elements with predicted properties.
D. the discovery of the nucleus.
13. Atoms of the most reactive elements tend to have
A. one or seven valence electrons.
B. eight valence electrons.
C. four or five valence electrons.
D. no valence electrons.
Answers
2. Highest melting point
3. Configuration
4. A
5. A
6. D
7. A
8. C
9. B
10. A
11. C
12. C
13. A
Final answer:
This answer explains chemical concepts related to the periodic table, atomic theory, the nature of molecules, and properties of subatomic particles.
Explanation:
1. Mendeleev organized elements in his periodic table in order of increasing atomic mass.
2. You would select the compound with the highest melting point as the ionic compound.
3. The types of atoms in the molecule and the shape of the molecule determine whether a molecule is polar.
4. According to Dalton, The ratio of their masses is always the same when elements combine in a compound.
5. Democritus thought that matter was made of tiny particles that could not be divided.
6. Rutherford’s gold foil experiment provided evidence that there is a dense, positively charged mass in the center of an atom.
7. It’s true that an electron has far less mass than either a proton or neutron.
8. Oxygen-17 and oxygen-18 are isotopes of oxygen.
9. In Bohr’s atomic model, electrons travel around the nucleus in fixed energy levels with energies that vary from level to level.
10. The electron cloud model describes the most likely locations of electrons.
11. An atom in an excited state has more energy, and is less stable than an atom in the ground state.
12. The usefulness of Mendeleev’s periodic table was confirmed by the discovery of elements with predicted properties.
13. Atoms of the most reactive elements tend to have one or seven valence electrons.
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Answers
Answer is: B. 2NaCl +H2SO4 ----> Na2SO4 + 2HCl.
According to principle of mass conservation, number of atoms must be equal on both side of balanced chemical reaction.
There are two sodium atoms, two chlorine atoms, two hydrogen atoms, one sulfur atom and four oxygen atoms on both side of balanced chemical reaction.
A) This reaction is not balanced, because number of oxygen atoms are not the same.
C) This reaction is not balanced, because number of oxygen and calcium atoms are not the same.
D) This reaction is not balanced, because number of sulfur atoms are not the same.
The equatin that is balanced is 2NaCl + H2SO4 → Na2SO4 + 2HCl. The answer is letter B. The reactant has two Na, 2 Cl, 2 H, 1 S and 4 O. These number of atoms is also the same for the product side.