Answer:
C. 6
Explanation:
The atomic number of a number is related to the number of protons in the nucleus.
According to the law of conservation of matter, which statement about chemical reactions is true? A. Atoms cannot be created or destroyed by chemical reactions. B. Atoms are created by some reactions and destroyed by others. C. Energy is created as atoms are destroyed in chemical reactions. D. Every atom destroyed in a chemical reaction must be replaced.
A 3.90 L sealed vessel under vacuum is filled with 6.40 g of fluorine gas. What is the pressure (in kPa) of the vessel at 25.0 ⁰C ?
From the ideal gas law, the pressure of the gas is 106 kPa.
First we must obtain the number of moles of the gas;
Number of moles = mass/molar mass
Molar mass of fluorine gas = 38 g/mol
Number of moles of F2 = 6.40 g/38 g/mol = 0.168 moles
Using the ideal gas equation;
PV = nRT
P = ?
V = 3.90 L
n = 0.168 moles
T = 25.0 ⁰C + 273 = 296 K
R = 8.314 kPa L K-1 mol-1
Substituting values;
P = nRT/V
P = 0.168 moles × 8.314 kPa L K-1 mol-1 × 296 K/3.90 L
P = 106 kPa
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The pressure of the vessel at a temperature of 25 °C is 106.73 KPa
We'll begin by calculating the number of mole of fluorine gas. This can be obtained as follow:
Mass of F₂ = 6.40 g
Molar mass of F₂ = 19 × 2 = 38 g/mol
Mole of F₂ =?Mole = mass / molar mass
Mole of F₂ = 6.40 / 38
Mole of F₂ = 0.168 moleFinally, we shall determine the pressure. This can be obtained as follow:
Volume (V) = 3.90 L
Temperature (T) = 25.0 °C = 25 + 273 = 298 K
Mole of F₂ (n) = 0.168 mole
Gas constant (R) = 8.314 L.KPa/Kmol
Pressure (P) =?PV = nRT
P × 3.9 = 0.168 × 8.314 × 298
P × 3.9 = 416.232096
Divide both side by 3.90
P = 416.232096 / 3.90
P = 106.73 KPaTherefore, the pressure of the vessel is 106.73 KPa
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(iii) Explain why magnesium chloride has a high melting point.
Answer:
magnesium chlorides are solids with high melting and boiling points because of the large amount of heat which is needed to break the strong ionic attractions.
Explanation:
These magnesium ions have more than one charge (2+). These highly charged ions will attract other ions more strongly than ions with one charge, therefore more energy will be needed to overcome the electrostatic forces of attraction and so the melting points will be higher.
Which is not a type of nuclear decay?
A. Zeta
B. Gamma
C. Alpha
D. Beta
Answer:
The answer is Zeta
Explanation:
The three types of nuclear decay are Gamma, Beta, and Alpha.
Why do you think dark surfaces absorb radiation better than light surfaces?
Your answer→ The lighter side absorbs less of the incident light, reflecting some of the energy. Darker materials also emit radiation more readily than light-colored materials, so they cool faster.
To solve this we must be knowing each and every concept related to radiation. Therefore, dark surfaces absorb radiation better than light surfaces as dark surfaces absorbs light of all wavelengths.
What is radiation?According to the energy of the emitted particles, radiation is frequently classified as being either ionizing or non-ionizing. More than 10 eV is often carried by ionizing radiation, which is sufficient to ionize atoms as well as molecules and rupture chemical bonds.
The word refers to radiation having an energy level high enough to ionize atoms, or to remove electrons from atoms to produce ions. Whenever an electron is removed from an atom's electron shell, or, as we may say, when it is "tried to knock out," the action of ionization takes place. Dark surfaces absorb radiation better than light surfaces as dark surfaces absorbs light of all wavelengths.
Therefore, dark surfaces absorb radiation better than light surfaces as dark surfaces absorbs light of all wavelengths.
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. The atomic number of a newly discovered element is found to be 128, and its mass number is 279.
How many protons, neutrons, and electrons are found in an ion of this element bearing a charge of
5−?
can someone help me please ... god will bless u if u help...it is very urgent... i only have 1hr to answer this question
Answer:
iuiwusiwuiqihihiuwusbhwubduywbduywbudb me no esspanlo
Explanation:
niuniniuniuniun
what is the difference between exergonic and exothermic reactions?
Answer:
An exergonic reaction is a type of chemical reaction that releases free energy to the surroundings. The final state of this reaction is less than its initial state. ... “Exothermic” literally means “outside heating” while “exergonic” literally means “outside work.”
Explanation:
If this helped you, please consider me for brainly!
Have a happy day <3 Miss Hawaii
How many mL of 1.76 M sodium hydroxide solution (strong base) must be added to 0.75
Macetic acid to make 683 mLa pH 49 buffer? (pka of acetic acid is 4.76)
Answer: Special care is required to prepare a solution of sodium hydroxide or NaOH in water because considerable heat is liberated by the exothermic reaction. The solution may splatter or boil. Here is how to make a sodium hydroxide solution safely, along with recipes for several common concentrations of NaOH solution.
Explanation:
Hope this helps!
If you have 4.01 g of H2, how many grams of NH3 can be produced?
Answer:
136.5886g of NH3
Explanation:
N2 + 3H2 = 2NH3
The mass of the N2 = 4.01
3H2 has a 2/1 ratio
This means the mass of 3H2 is twice as much as N2.
NH3= 2*N2 = 2*4.01 = 8.02 of NH3
Then, by multiplying the mass by MX (17.031)
8.02*17.031=136.5886g can be produced. Round it if needed.
5. A student measures the mass of an object three times on a balance in order to calculate the objects
density. The recorded masses are 70.21 g, 64.55 g, and 74.70 g. The accepted value for the mass of
the object is 70.21 g.
a. Are these measurements accurate? Why or why not?
b. Are the measurements precise? Why or why not?
Answer:
This is not chemistry this is physics
Consider:
2Al (s) + 3Cl2 (g) ----> 2AlCl3 (s) ΔH=-1390.81 kJ
Which of the following correctly describes he magnitude and direction of the enthalpy change when 10.0g of AlCl3 forms?
a. 104.4 kJ, exothermic
b. 52.2 kJ, exothermic
c. 26.1 kJ, exothermic
d. 52.2 kJ, endothermic
e. 26.1 kJ, endothermic
Answer:
The answer is B.
Explanation:
1 mole of AlCl3 = 27 + 3*35.5 grams = 133.5 grams
1 mole / 133.5 = x / 10 Cross multiply
133.5 x = 1 * 10
x = 10 / 133.5
x = 0.0749 moles
Delta H when written the way it is, is on the left side and since it is negative, the reaction must give away 1390.81 kj. The reaction is exothermic.
So now you get the answer between AB and C by setting up a ratio.
2/0.0749 = -1390.81 / x Cross multiply
2x = 0.0749 * -1390.81
2x =- 104.18 Divide both sides by 2
2x//2 = -104.18 / 2
x = -52.09
B
Which statement describes the bonds in nitrate (NO3-)?
A) Nitrogen and oxygen have an electronegativity difference of 0.5, so the bond is polar covalent, with oxygen pulling the electrons toward it.
B) Nitrogen and oxygen have an electronegativity difference of 0.5, so the bond is nonpolar covalent.
C) Nitrogen and oxygen have an electronegativity difference of 0.5, so the bond is ionic.
D) Nitrogen and oxygen have an electronegativity difference of 0.5, so the bond is polar covalent, with nitrogen pulling the electrons toward it.
The bond in NO3- ion is polar covalent and oxygen pulls the electrons.
A polar covalent bond is formed when there is a significant difference in electronegativity between covalently bonded atoms.
Such bonds are said to be polar covalent with the electron density tilted towards one of the bonding atoms.
In NO3-, Nitrogen and oxygen have an electronegativity difference of 0.5, so the bond is polar covalent, with oxygen pulling the electrons toward it.
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The answer is A, Nitrogen and oxygen have an electronegativity of 0.5, so the bond is polar covalent, with oxygen pulling the electrons toward it.
Electronegativity is defined as, a value that describes the relative strength with which an atom of an element attracts electrons to itself in a chemical bond. Moreover, electronegativity can be used to define a bond.
A electronegativity of 0.5-1.7 is determined to be a polar covalent bond, thus the bonds in nitrate is polar covalent.
We know that electronegativity increases on the periodic table across a period, but decreases down a group. Thus, oxygen has a greater electronegativity than nitrogen.
The change in internal energy for the combustion of cyclohexanol (C6H12O) is -890.7 Kcal per mole. A .708 g sample of cyclohexanol undergoes complete combustion in a bomb calorimeter that has a heat capacity of 2.70 Kcal per degree C. What is the final temperature of the water in the calorimeter if the initial water temperature is 27C?
The final temperature in the calorimeter, with a heat capacity of 2.70 kcal/°C, internal energy for the combustion of cyclohexanol (C₆H₁₂O) of -890.7 kcal/mol and initial temperature of 27°C, is 29.33 °C.
We can find the final temperature of the water in the calorimeter with the following equation:
[tex]\Delta E = -C\Delta T = -C(T_{f} - T_{i})[/tex] (1)
Where:
ΔE: is the change in internal energy for the combustion of C₆H₁₂O = -890.7 Kcal/mol
C: is the heat capacity of the calorimeter = 2.70 Kcal/°C
[tex]T_{f}[/tex]: is the final temperature =?
[tex]T_{i}[/tex]: is the initial temperature = 27 °C
By solving equation (1) for [tex]T_{f}[/tex], we have:
[tex] T_{f} = -\frac{\Delta E}{C} + T_{i} [/tex]
[tex]T_{f} = -\frac{-890.7 \frac{kcal}{mol\: C_{6}H_{12}O}*\frac{1 mol \: C_{6}H_{12}O}{100.158 g \: C_{6}H_{12}O}*0.708 g \: C_{6}H_{12}O}{2.70 kcal/^{\circ}C} + 27 ^{\circ}C = 29.33 ^{\circ}C[/tex]
Therefore, the final temperature of the water is 29.33 °C.
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I hope it helps you!
A force of 500 N acts over an area of 10 m2. Use the
formula to calculate the pressure.
Answer:
50Pa
Explanation:
pressure= force/area
= 500N/10m2
= 50Pa
helppppppppppppppppppppppppp
True
All matter is made up of atoms.
im guessing it probably true
Alka-Seltzer is pure NaHCO3
True or false?
Answer:
falso
Explanation:
PLS HELP WORTH 25 POINTS WILL MARK BRAINLIEST IF CORRECT
Examine the false statement. When pressure is added to a reaction at chemical equilibrium, the reaction responds by increasing the amount of pressure it exerts on its surroundings. Select the rewording that makes the statement true.
A. When pressure is added to a reaction at chemical equilibrium, the reaction responds by increasing the rate of reaction, which will decrease the number of particles and offset the pressure.
B. When pressure is removed from a reaction at chemical equilibrium, the reaction responds by decreasing the amount of pressure it exerts on its surroundings.
C. When pressure is removed from a reaction at chemical equilibrium, the reaction responds by increasing the rate of reaction, which will decrease the number of particles and increase the pressure.
D. When pressure is removed from a reaction at chemical equilibrium, the reaction responds by decreasing the amount of pressure it releases to its surroundings.
E. When pressure is added to a reaction at chemical equilibrium, the reaction responds by decreasing the amount of pressure it absorbs from its surroundings.
IT'S NOT C OR E
Answer:
A i think. Good luck!!!!
Câu 15: Nguyên tử X nặng gấp 2 lần nguyên tử cacbon. Nguyên tử X đó có nguyên tử khối và
kí hiệu hóa học là
A. 24_Mg. B. 16_O C. 56_Fe D. 32_S
Answer:
A
Explanation:
Which has more calories: table sugar or aspartame?
Answer:
Aspartame produces 4 kilocalories of energy per gram when metabolized, sucrose (table sugar) produces 3.9 kilocalories. However, aspartame is approximately 200 times sweeter than sucrose, so it is consumed in much smaller doses.
Explanation:
Answer is Aspartame.
5. The density of a gas is lower than the density of a liquid because:
a. gas atoms are smaller than liquid atoms.
b. gas atoms are larger than liquid atoms
c. atoms in a gas are farther apart than atoms in a liquid.
d. atoms in a gas are closer together than atoms in a liquid
Answer:
c
Explanation:
the gas is further apart and the liquid is closer together
A compound's properties are different than the properties of the elements that make it up.
A)True
B)False
The electronic transition in a hydrogen atom from n = 6 to n = 3 emits electromagnetic radiation having a higher frequency than a transition
from n = 5 to n = 3
what happens to a circuits resistance (R), voltage (V), and current (I) when you increase the diameter of the wire in the circuit?
a. R increases, V is constant, I increases
b. R decreases, V is constant, I increases
c. R decreases, V increases, I increases
d. R increases, V decreases, I decreases
Answer:
b. R decreases, V is constant, I increases
Explanation:
when we increase the diameter of wire increases ,resistance decreases and current increases.Therefore, the option is b.
Resistance is an electrical quantity which opposes the electric current in the circuit. Resistance is directly proportional to the length of the wire and inversely proportional to the diameter of the wire. If length of wire increases resistance will increases and if the diameter of the wire increase resistance will decreases.
R = ρ L/A
Here ρ is the resistivity
L is the length of the wire
A is the cross-sectional area of wire/diameter of the wire
Voltage is the potential difference between two terminals of voltage source. Current is the flow of electrons in the circuit. Voltage is the product of current and resistance.
V=IR
Rewrite the above equation interms of current
I=V/R
From the above equation we can say that current is inversly proportional to the resistance.Therefore,the correct option is b.
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Please solve this question
Answer:
what question?
Explanation:
Can you help me solve this ?
What mineral is composed of sodium chloride (NaCl)?
Answer:
Salt
Explanation:
The mineral form halite , or rock salt is sometimes called common salt
What is the lead concentration of a saturated solution of lead(II) sulfate containing 0.020 M Na2SO4? Ksp for PbSO4 = 6.3x10-7.
Answer:
i want to help but i d k. the answer :( sorry i couldnt help
Explanation:
When doing medical research with human subjects, which four limitations are unavoidable?
Answer:
Answer
The limitations are-
1. Privacy of the individuals involved in the research process.
2. Physical and psychological risks should be minimized
3. The subjects should be chosen equitably
4. Only reasonable exposure to risks is admissible.
Explanation
The privacy of the individuals involved in the research must be taken into consideration. This will ensure safety of patient data and information. The risk of physical and physiological well being of the person must be taken into consideration in such a research. In addition to that, the subject must be made to understand every procedure and the risks involved before testing. Moreover, only minimal exposure to risks is allowed and must have been previously tested in animals to avoid deaths.
wat are the dangers of chemicals in the laboratory