Answer:
Explanation:
Describe means you should recall facts, events or processes accurately. You might need to give an account of what something looked like, or what happened.
Explain means you need to make something clear, or state the reasons for something happening.
Compare means you need to describe similarities and differences between things. If you are asked to compare X and Y, write down something about X and something about Y, and give a comparison. Do not just write about X only or Y only.
Evaluate means you must use information supplied, or your own knowledge, to consider the evidence for and against or to identify strengths and weaknesses. You must then complete your answer with a conclusion, stating which is better and why, for example.
How many grams of H2S is needed to produce 18.00g of PbS if the H2S is reacted with an
excess (unlimited) supply of Pb(CH3COO)2?
Answer:
2.56 grams of H₂S is needed to produce 18.00g of PbS if the H2S is reacted with an excess (unlimited) supply of Pb(CH₃COO)₂
Explanation:
The balanced reaction is:
Pb(CH₃COO)₂ + H₂S → 2 CH₃COOH + PbS
By stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction) they react and produce:
Pb(CH₃COO)₂: 1 moleH₂S: 1 moleCH₃COOH: 2 molesPbS: 1 moleIn this case, to know how many grams of H₂S are needed to produce 18.00 g of PbS, it is first necessary to know the molar mass of the compounds H₂S and PbS and then to know how much it reacts by stoichiometry. Being:
H: 1 g/moleS: 32 g/molePb: 207 g/moleThe molar mass of the compounds are:
H₂S: 2* 1 g/mole + 32 g/mole= 34 g/molePbS: 207 g/mole + 32 g/mole= 239 g/moleSo, by stoichiometry they react and are produced:
H₂S: 1 mole* 34 g/mole= 34 gPbS: 1 mole* 239 g/mole= 239 gThen the following rule of three can be applied: if 239 grams of PbS are produced by stoichiometry from 34 grams of H₂S, 18 grams of PbS from how much mass of H₂S is produced?
[tex]mass of H_{2} S=\frac{18 grams of PbS*34 grams of H_{2}S }{239 grams of PbS}[/tex]
mass of H₂S= 2.56 grams
2.56 grams of H₂S is needed to produce 18.00g of PbS if the H2S is reacted with an excess (unlimited) supply of Pb(CH₃COO)₂
Another name for a statovolcano is a _____ volcano because it is made of alternating layers of thick, sticky lava and volcanic rock and ash. A. shield B. cinder C. composite D. pyroclastic
Answer:
Bcinder
Explanation:
whats the chemical formula for dilute hydroxide acid
URGENT!!!!
An ordered list of chemical substances is shown.
Which substances in the list can be some of the reactants and products in the same combustion reaction? (4 points)
Select one:
a. 1, 2, and 3
b. 2, 3, and 6
c. 1, 4, and 5
d. 1, 2, and 5
Answer : The correct option is (b) 2, 3, and 6
Explanation :
Combustion reactions: It is defined as the reactions in which a hydrocarbon reacts with oxygen gas to produce carbon dioxide and water.
A balanced chemical equation is defined as the equation in which total number of individual atoms on the reactant side is equal to the total number of individual atoms on product side.
The general chemical equation for the combustion is as follows:
[tex]C_xH_yO_z+O_2\rightarrow CO_2+H_2O[/tex]
where, 'x', 'y' and 'z' are the subscripts of Carbon, hydrogen and oxygen respectively.
The reactants and products in the same combustion reaction are [tex]O_2[/tex] and [tex]CO_2,H_2O[/tex] respectively.
Hence, the correct option is (b) 2, 3, and 6
2 Points
A student blows a whistle. In which direction do the air particles vibrate with
respect to the direction the sound wave travels?
A. Perpendicular to
B. Parallel to
C. At a 45 degree angel to
D. At an unpredictable angel
Answer:
parallel to
Explanation:
In parallel direction the air particles vibrate with respect to the direction the sound wave travels. The correct option is B.
What is sound wave?A sound wave is the pattern of disturbance caused by the movement of energy as it propagates away from the source of the sound through a medium (such as air, water, or any other liquid or solid matter).
Sound waves are produced by object vibrations and pressure waves, such as a ringing cellphone.
Because sound waves are produced by compressions and rarefactions in the air, they are referred to as longitudinal waves. The air particles vibrate in a direction parallel to the propagation direction.
The particles in a longitudinal wave are displaced parallel to the direction of the wave. Compressions moving along a slinky are an example of longitudinal waves.
Air particles vibrate in a parallel direction to the direction of travel of the sound wave.
Thus, the correct option is B.
For more details regarding sound waves, visit:
https://brainly.com/question/21995826
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PLS HELP ! 5.00 mL of a stock solution, containing 0.200 M of Na3PO4 was pipetted into a 25.00 mL volumetric flask and made up to the calibration mark with deionised water. A serial dilution was carried out for another two times to obtain the final solution of desired concentration. Calculate the concentration of the final solution, express in ppm (by volume).
Answer:
262 ppm of Na₃PO₄
Explanation:
In a dilution, the concentration of the initial solution is decreased. When you take 5.00mL of the solution that is diluted to 25.0mL The solution is diluted 25/5 = 5 times
If you make another two serial dilutions the final solution wil decrease its concentration 5*5*5 = 125 times
As original solution containing 0.200 M of Na3PO4, the final solution will have a concentration of:
0.200M / 125 = 1.6x10⁻³M
Molarity is defined as the ratio between moles and liters. 1.6x10⁻³ moles of Na3PO4 in 1L are:
1.6x10⁻³mol ₓ (164g/mol) = 0.262g Na₃PO₄ / L
Assuming density of Na3PO4 as 1g/mL the concentration of the solution is:
0.262mL Na₃PO₄ / L
As 1mL = 1000μL:
262μL Na₃PO₄ / L
μL of solute per L of solution is equal to ppm, that means the solution has:
262 ppm of Na₃PO₄Jaiden is writing a report about the structure of the atom. In her report, she says that the atom has three main parts and two subatomic particles. Do you agree with her? Why or why not?
Answer:
The smallest constituent of an element is termed as an atom. According to Jaiden, an atom comprises two subatomic particles and three prime parts, however, this is incorrect as an atom comprises three subatomic particles and two main parts. The three subatomic particles are the protons, electrons, and neutrons. All these parts are smaller in comparison to an atom, thus, they are considered as subatomic particles.
To be considered as an atom, an atom is needed only electrons and neutrons, like hydrogen exhibit one electron and one proton. On the other hand, the overall charge of the atom is not affected by the presence of neutrons, it is the subatomic particle that only enhances the mass of the atom.
Answer:
I disagree with her because an atom has two main parts: the nucleus and the electron cloud. Atoms have three subatomic particles: protons, neutrons, and electrons.
Explanation:
Another chemistry question. Help me!
To prepare 250cm³ of standard solution of 1.0 mol dm-³ sodim carbonate Na2Co3
Answer:
Molar mass Na2CO3 = 2*23 + 12 + 3*16 = 106 g/ mol
Mass of 1 mol Na2CO3 = 106 g
mass (Na2CO3) = 106g*250cm³/1000cm³ = 26.5 g
1) It is necessary because all Na2CO3 will be in the solution, and no Na2CO3 would be lost.
2) Because the solution that was formed after rinsing beaker contains Na2CO3.
3) Eyes should be on the level of calibration mark of the volumetric flask.
4) It is necessary to prevent evaporation of water, and changing , because of it, the concentration of the solution.
Which element is needed for
a. Bone and teeth formation.
b. Treatment of water.
Answer:
a.calcium
b.chlorine
Name two drying agents that can be use to dry hydrogen gas