Which of the following types of mixtures exhibit the Tyndall effect?a. solutions
c. colloids
b. suspensions
d. none of the above
Answers
Colloids have small non-dissolved particles that flow around in the mixture. These particles do not settle over time. When a light is shined on colloids the scattering characteristic of the Tyndall effect are visable.
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Compared to the atoms of nonmetals in period 3, the atoms of metals in period 3 have1. fewer valence electrons 2. more valence electrons 3. fewer electron shells4. more electron shells
Which of the following is not a type of basic structure for a pure metal?
is an endothermic process. A 6.1589-g sample of the solid is placed in an evacuated 4.000-L vessel at exactly 24°C. After equilibrium has been established, the total pressure inside is 0.709 atm. Some solid NH4HS remains in the vessel.
(a) What is the KP for the reaction?
(b) What percentage of the solid has decomposed?
(c) If the volume of the vessel were doubled at constant temperature, what would happen to the amount of solid in the vessel?
Answers
Answer:
(a) Kp = 0.126
(b) 48.1 %
(c) More of the solid will decompose, therefore it will decrease.
Explanation:
(a) We have here the equilibrium decomposition of NH₄HS, according to the equation:
NH₄HS (s) ⇄ NH₃ (g) + H₂S
with an equlibrium cosnstant, Kp, given by
Kp = pNH₃ x pH₂S
where pNH3 and pH₂S are the partial pressures of NH₃ and H₂S .
Since 1 mol NH₃ is produced for every 1 mol H₂S, it follows that the partial pressure of NH₃ is equal to the partial pressure of H₂S ( from ideal gas law the pressure is proportional to number of mol):
pNH₃ = pH₂S = 1/2 (0.709) atm = 0.355 atm
and
Kp = 0.355 x 0.355 = (0.3545) ² = 0.126
(b) To solve this part we need to do a calculation based on the stoichiometry of the reaction by calculating the number of moles, n, a partial pressure of 0.355 atm represent.
From the ideal gas law we can calculate it:
PV = nRT ⇒ n = PV/RT
where P = 0.355 atm, V = 4.000 L, T = ( 24 + 273 ) K, and R is the gas constant 0.08205 Latm/Kmol.
n = 0.355 atm x 4.000 L / 0.08205 Latm/Kmol x 297
n = 0.058 mol
Now we can relate this 0.058 mol of NH₃ ( or H₂S ) to the number of moles of moles of NH₄HS that must have decompesed. Since it is a 1: 1 ratio:
(1 mol NH₄HS / 1 mol NH₃ ) x 0.058 mol NH₃ = 0.058 mol NH₄HS
Having the molar mass of NH₄HS, 51.11 g/mol we can calculate its mass:
0.058 mol NH₄HS x 51.11 g/mol = 2.9644 g
Percentage decomposition is then equal to:
2.9644 / 6.1589 g x 100 g = 48.1 %
(c) If the volume of the vessel, effectively we are reducing the pressure by a half , and the system will react according to LeChatelier's principle by producing more gaseous products to reach equilibrium again. Therefore, more of the solid NH₄HS will decompose, and the amount of it will we reduced compared to the previous part.
b.compound
c.mixtures
d.solution
Answers
A compound is a substance in which all the exact combinations of elements are always the same. The correct option is b.
What is a compound?
Compounds are substances that are made up of two or more substances or elements. A compound is a mixture of two elements, they share bonds with each other, and they form a totally different substance than the above elements.
For example, NaCl is a compound. It is formed by two elements, sodium, and chloride. These elements form a different compound that is common table salt.
Some compounds are pure substances because they are made up of only elements that mix together. They do not contain any impurity or any other substance. They share chemical bonds with each other.
Thus, the correct option is b. compound.
To learn more about compounds, refer to the link:
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source is Glencoe Science book grade 7.
Also I just happening to be learning about this at school
sublimation
boiling
evaporation
Answers
The answer is sublimation.
Sublimation is the chemical process whereby a solid turns into a gas without first becoming a liquid.
The word sublimation comes from the Latin word sublimare which means "raised to a higher status."
Examples of sublimation include surface layer of snow and ice turning into steam or fog without melting and dry ice which is the solid form of carbon dioxide which also undergoes sublimation.
The low temperature and sublimation makes dry ice an effective coolant or cooling agent . One of its main advantages is that it has a lower temperature than water ice and also does not leave any residue.
Answer: Sublimation
Explanation: Gradpoint
b. 4
c. 8
d. 16
Answers
There are eight hydrogen atoms in the following molecule of ammonium sulfide. Thus, the correct option for this question is C.
What is a Molecule?
A molecule may be defined as a cluster of atoms that are significantly bonded together in order to represent the smallest basic unit of a chemical compound that can involve in a chemical reaction.
According to this question, the correct representation of ammonium sulfide is , where the number of the hydrogen atoms is equal to 4 × 2 = 8. Apart from this, the number of nitrogen atoms is 2. While the number of sulfur atoms is only 1.
Therefore, there are eight hydrogen atoms in the following molecule of ammonium sulfide. Thus, the correct option for this question is C.
To learn more about Molecules, refer to the link:
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Answers
You can then calculate that 3.6L of Hydrogen contains 0.16mol
1mol/22.4L x 3.6L = 0.16mol
Every 2 moles of Hydrogen require 1 mole of oxygen to form water. Therefore half of the number of moles of oxygen are required.
0.16mol/2 = 0.08mol
Again, we know that at STP 1 mol occupies 22.4L
0.08mol x 22.4L/mol = 1.79L of O2 needed.
Also 3.6/2 = 1.8 All ideal gasses will occupy the same ammount of space at STP
Answers
When an uncharged pith ball is brought into the electrostatic field of a charged tod, the side of the pith ball closest to the negatively charged end of the rod will also gain a negatively charged surface. Then, it will not attract to the charged tod but rather it will repel.
I need the answer asap