How many calories of heat energy are required to melt 20 grams of ice at 0 °c?
What new inforamtion can you add the your definition of physical change?
There are ________ hydrogen atoms in 25 molecules of c4h4s2.
Answer: 100.
Explanation:
1) The subscripts to the right of each element (symbol) in the chemical formula tells the number of atoms of that element present in one unit formula.
2) The unit formula of C₄H₄S₂ is equal to 1 molecule.
3) Therefore, there are 4 carbon atoms, 4 hydrogen atoms and 2 sulfur atoms in each molecule of C₄H₄S₂.
4) Then, you just have to multiply the corresponding subscript of the element times the number of molecules (25 in this case) to find the number of atoms of that kind.
5) These are the calculations for each element in the molecule C₄H₄S₂.
i) C: 4 × 25 = 100
ii) H: 4 × 25 = 100
iii) S: 2 × 25 = 50.
6) The question is about H only, so the answer is that there are 100 hydrogen atoms in 25 molecules of C₄H₄S₂.
Silver has a density of 10.5 g cm3 and gold has a density of 19.3 g/cm3. which would have the greater mass, 5cm^3 of silver or 5cm^3 of gold?
In which medium would light have the longest wavelength? water air glass diamond
the answer is b air
what would you notice about the dot diagram of an unstable element?
The dot diagram of an unstable element has incompletely filled shell that is it will not have 8 dots which represent a stable octet.
What is an element?
It is defined as a substance which cannot be broken down further into any other substance. Each element is made up of its own type of atom. Due to this reason all elements are different from one another.
Elements can be classified as metals and non-metals. Metals are shiny and conduct electricity and are all solids at room temperature except mercury. Non-metals do not conduct electricity and are mostly gases at room temperature except carbon and sulfur.
The number of protons in the nucleus is the defining property of an element and is related to the atomic number.All atoms with same atomic number are atoms of same element.
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Assuming complete dissociation, what is the molality of k+, br− in an aqueous solution of kbr whose freezing point is -2.53 ∘c? the molal freezing-point-depression constant of water is 1.86 (∘c⋅kg)/mol.
If a 3.30 m sample of a is heated to 500 k, what is the concentration of b at equilibrium?
To find the concentrations at equilibrium, one would use the equilibrium constant (K). Given known concentrations and the stoichiometry of the reaction, one can solve for the unknown concentration. Be sure to convert all quantities to appropriate units (molarity), and remember that these calculations assume that the system is at equilibrium.
Explanation:The question pertains to chemical equilibrium, particularly the equilibrium for the reaction N₂(g) + 3H₂(g) = 2NH3(g) at 500 k. It seems like there could be some missing details in the question, so I'll provide a general approach to solving problems like this.
To find the concentrations at equilibrium, we can use the concept of equilibrium constants. In this case, the equilibrium constant (K) for the reaction N₂(g) + 3H₂(g) = 2NH3(g) would be expressed as K = [NH3]² / ([N2][H2]³). Plugging in the known concentrations, one can solve for the unknown, which might be the concentration of 'b' referred to in the original question.
Note that the concentrations should be in molarity (M) units, which represent moles of solute per liter of solution. Therefore, the 3.30 m sample needs to be converted into volume (in litres) to derive the molarity given the number of moles of the substance.
Remember that calculations with equilibrium constants assume that the system has reached equilibrium, and that temperature remains constant. If the actual situation doesn't meet these conditions, more complex calculations might be needed.
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Which of these practices does the most to keep wind and water from carrying away topsoil?
A. Crop rotation
B. Integrated pest management
C. Drip irrigation
D. Cover crops
Answer:
The correct answer is Cover Crops
In the diagram, above, marker D is pointing to a __________, which is a landform that forms when a river slows down as it flows into an ocean or lake. As the river slows, it drops its sediment load, gradually creating a network of small channels and islands.
What is the molar mass of the empirical formula for a compound with the formula C6H12Cl2O2
The molar mass of the empirical formula CH2ClO for the compound C6H12Cl2O2 is 65.476 g/mol, calculated by summing the atomic masses for carbon, hydrogen, chlorine, and oxygen.
The student is asking about the molar mass of the empirical formula for a compound with the formula C6H12Cl2O2. An empirical formula represents the simplest whole-number ratio of the elements within a compound.
For the given compound, its empirical formula is CH2ClO. To find the molar mass of this empirical formula, we sum the atomic masses of each element, adjusting for the number of atoms present. The atomic masses are approximately 12.01 g/mol for carbon (C), 1.008 g/mol for hydrogen (H), 35.45 g/mol for chlorine (Cl), and 16.00 g/mol for oxygen (O).
The calculation is as follows:
(1 \\u00d7 12.01 g/mol) for C(2 \\u00d7 1.008 g/mol) for H(1 \\u00d7 35.45 g/mol) for Cl(1 \\u00d7 16.00 g/mol) for OAdding them together, the molar mass of the empirical formula CH2ClO is:
12.01 + (2 \\u00d7 1.008) + 35.45 + 16.00 = 65.476 g/mol.
Therefore, the molar mass of the empirical formula for the compound is 65.476 g/mol.
Which hypothesis led to the discovery of the proton?
Answer:
a ) when a neutral hydrogen atom loses an electron, a positively-charged particle should remain
A rigid vessel at constant temperature initially contains 0.600 atm nitrogen gas and 0.600 atm hydrogen gas. if these gases react to form ammonia and the reaction goes to completion, which choice is closest to the final total pressure after the reaction?
The final total pressure after the completion of reaction is [tex]\boxed{0.8{\text{ atm}}}[/tex].
Further Explanation:
Stoichiometry:
The amountof species present in the reaction is determined with the help of stoichiometry by the relationship between reactants and products.
Balanced chemical reaction between nitrogen and hydrogen is as follows:
[tex]{{\text{N}}_{\text{2}}} + 3{{\text{H}}_2} \to 2{\text{N}}{{\text{H}}_{\text{3}}}[/tex]
This balanced reaction’s stoichiometry clearly indicates that one mole of nitrogen reacts with three moles of hydrogen to produce two moles of ammonia.
Since pressure is directly related to number of moles of gas, pressure required by hydrogen to react with one mole of nitrogen should be three times of pressure of nitrogen.
Therefore pressure of hydrogen can be calculated as follows:
[tex]\begin{aligned}{\text{Pressure of hydrogen}} &= 3\left( {0.600{\text{ atm}}} \right) \\&= 1.8{\text{ atm}} \\\end{aligned}[/tex]
But pressure of hydrogen in the rigid vessel is 0.600 atm only so it behaves as limiting reactant and its amount will govern the amount or quantity of product formed (ammonia).
Since the ratio of pressures of hydrogen and ammonia is 3:2, pressure of ammonia can be calculated as follows:
[tex]\begin{aligned}{\text{Pressure of ammonia}} &= \left( {\frac{2}{3}} \right)\left( {0.600{\text{ atm}}} \right) \\&= 0.4{\text{ atm}} \\\end{aligned}[/tex]
Pressure of unreacted nitrogen can be calculated as follows:
[tex]\begin{aligned}{\text{Pressure of unreacted nitrogen}} &= \left( {\frac{2}{3}} \right)\left( {0.600{\text{ atm}}} \right) \\&= 0.4{\text{ atm}} \\\end{aligned}[/tex]
Therefore total final pressure after the reaction can be calculated as follows:
[tex]\begin{aligned}{\text{Total final pressure}} &= \left( {0.4 + 0.4} \right){\text{ atm}} \\&= {\text{0}}{\text{.8 atm}} \\\end{aligned}[/tex]
Learn more:
Calculate the moles of chlorine in 8 moles of carbon tetrachloride: https://brainly.com/question/3064603 Calculate the moles of ions in the solution: https://brainly.com/question/5950133
Answer details:
Grade: Senior School
Subject: Chemistry
Chapter: Mole concept
Keywords: stoichiometry, NH3, H2, N2, pressure, hydrogen, nitrogen, ammonia, 0.4 atm, 1.8 atm, 0.600 atm, 3H2, 2NH3, 0.8 atm.
In what three catagories can chemical reactions be classified
Example 1: urea, (nh2)2co, is used in the manufacture of resins and glues. when 5.00 g of urea is dissolved in 250.0 ml of water (d = 1.00 g/ml) at 30.0 c, 27.6 kj of heat is absorbed. (specific heat of water 4.18 j/g.c) is the solution process exothermic? what is ? what is the final temperature of solution?
trampoline and playground
A carbon compound X turns blue litmus to red and has a molecular formula C2H4O2.Identify X and draw its structure.Write a chemical equation for the reaction and name of the product formed in each case when X reacts with
a. ethanol in the presence of conc.H2SO4 (
b. sodium carbonate
Answer: Substance X is ethanoic acid and the reactions are given below.
Explanation:
A compound having molecular formula of [tex]C_2H_4O_2[/tex] which turns blue litmus to red is considered as an acid.
The compound is ethanoic acid which is generally termed as acetic acid.
Thus, the compound X is acetic acid.
The chemical equations for the reaction of X with
a. Ethanol in the presence of [tex]H_2SO_4[/tex]When acetic acid reacts with etahnol in the presence of an acid, it leads to the formation of a fruity smelling compound known as ester which is ethyl acetate.
[tex]CH_3COOH+CH_3CH_2OH\xrightarrow[]{H_2SO_4}CH_3COO-CH_2CH_3+H_2O[/tex]
b. Sodium carbonateWhen acetic acid reacts with sodium carbonate, it leads to the formation of sodium acetate, carbon dioxide and water.
[tex]2CH_3COOH+Na_2CO_3\rightarrow 2CH_3COONa+CO_2+H_2O[/tex]
fast-moving glaciers that can move up to 6 kilometers per year.
Surging glaciers experience a significant increase in movement, moving at speeds much faster than the average glacier.
A glacial surge is a sudden increase in the speed of a glacier, often moving tens of meters per day, which is significantly faster than the typical glacier movement. Glaciers generally move by pseudo-plastic flow and their velocity is greatest at the surface, tapering off towards the base due to internal deformation and basal slipping. While average glacier speed is around 10 inches per day, surging glaciers can greatly exceed this, with some known to move up to 6 kilometers per year.
Notable examples of surging glaciers include the Hubbard Glacier, which in 1986 surged across the Russell fjord, and Greenland's fast-moving Jakobshavn glacier. Surging can be caused by various factors, but one believed to be significant is the buildup of water pressure beneath the glacier, which effectively 'floats' the ice, letting it slip over the bedrock. The presence of looped moraines on the glacier surface is a key indicator of a surging glacier.
SUPER EASY!
12 POINTS
Choose all that apply.
Which of the following contribute to your body's digestive process?
muscle
movements
chemical reactions
physical processes
respiration
Hydrazine (n2h4) is used as rocket fuels. it reacts with oxygen to form nitrogen and water. write the balanced equation for this reaction. n2h4 + o2 → n2 +2h2o how many liters of n2 at stp form when 100g of n2h4 reaction with 100g of o2? how many grams of the excess reagent remain after the reaction?
The answer is: volume of nitrogen is 70L.
Chemical reaction: N₂H₄ + O₂ → N₂ + 2H₂O.
m(N₂H₄) = 100 g; mass of hydrazine.
M(N₂H₄) = 32 g/mol; molar mass of hydrazine.
n(N₂H₄) = m(N₂H₄) ÷ M(N₂H₄).
n(N₂H₄) = 100 g ÷ 32 g/mol.
n(N₂H₄) = 3.125 mol; amount of hydrazine.
m(O₂) = 100 g; mass of oxygen.
M(O₂) = 32 g/mol; molar mass of oxygen.
n(O₂) = 100 g ÷ 32 g/mol.
n(O₂) = 3.125 mol; amount of oxygen.
From chemical reaction: n(O₂) : n(N₂) = 1 : 1; n(O₂) = n(N₂).
n(N₂) = 3.125 mol; amount og nitrogen gas.
V(N₂) = n(N₂) · Vm.
Vm = 22.4 L/mol; molar volume.
V(N₂) = 3.125 mol · 22.4 L/mol.
V(N₂) = 70 L.
There is not excess reagent, because hydrazine and oxygen are all used in chemical reaction.
What is my theoretical yield (in moles) of Potassium Bromide (KBr) if I start with 40 grams of Iron (II) Bromide [FeBr2]? moles KBr
A compound has the empirical formula CH2O. If the compound’s molecular mass is 180 g/mol, determine the molecular formula of the compound. Be sure to show your work.
Based on a kc value of 0.200 and the given data table, what are the equilibrium concentrations of xy, x, and y, respectively? express the molar concentrations numerically.
Without additional data from the data table regarding initial concentrations and change, we cannot calculate the equilibrium concentrations of XY, X, and Y based on the provided Kc value. An ICE table and the presumed small value of x in concentration changes are needed to employ the equilibrium constant effectively.
To calculate the equilibrium concentrations of XY, X, and Y based on the given Kc value of 0.200, we need additional data from the data table. The statement mentions XY, X and Y but only provides information about X2, Y2, and Ke. Assuming we are dealing with a chemical equilibrium that can be represented as:
X2 + Y2 → 2XY
A mathematical expression for the equilibrium constant Kc can be written as:
[tex]Kc = [XY]^2 / ([X2][Y2])[/tex]
Since an ICE table and initial concentrations are not provided in the question, we cannot calculate the equilibrium concentrations without that information. Additionally, Ke may refer to the equilibrium constant in terms of pressure (Kp), so it's unclear how to proceed without more context. The provided value of Ke or Kc needs to be used with the initial concentrations to determine equilibrium concentrations after setting up an ICE (Initial, Change, Equilibrium) table. Typically, to find x (the change in concentration), we assume x is small and can be ignored in the expressions (0.78 - x) and (0.21 - x) considering the very small Kc value, leading to a simplification in solving the equation for x, if applicable.
Valence electrons are responsiblefor the makeup of chemical properties of elements true or false
Answer:
WRONG-the answer is TRUE
Explanation:
Assume that 1.0 mol of C4H10 is completely burned in excess oxygen to form carbon dioxide and water. How many moles of CO2 would be produced?
Final answer:
The complete combustion of 1.0 mole of C4H10 (butane) in excess oxygen will produce 4 moles of carbon dioxide (CO2).
Explanation:
To determine how many moles of carbon dioxide (CO₂) are produced when 1.0 mole of C₄H₁₀ (butane) is completely burned in excess oxygen, we need to first write and balance the chemical equation for the combustion of butane. The balanced chemical equation for the combustion of butane is:
C₄H₁₀ + 6.5O₂ → 4CO₂ + 5H₂O
This equation shows that 1 mole of butane reacts with 6.5 moles of oxygen to produce 4 moles of CO₂ and 5 moles of water (H₂O). Therefore, the complete combustion of 1.0 mole of C₄H₁₀ will produce 4 moles of carbon dioxide.
One way the modern atomic model differs from Thomson's atomic model is that electrons are no longer scattered throughout and atom's positive matter like chocolate chips in a cookie dough. instead, each electron is outside of the nucleus occupying a specific ___
When taking measurements, you must consider _____.
- accuracy, precision, and uncertainty
- only accuracy
- only precision
- only uncertainty
Which of these agreements has goals of peace and shared scientific research?
A. Environmental Protection Treaty
B. Migratory Bird and Game Mammal Treaty
C. Antarctic Treaty System
D. Ramsar Convention
Option C, Antarctic Treaty System, is the right answer.
The Antarctic Treaty System, control global connections with regard to Antarctica; the only continent of the earth without the native population of human beings. In other words, the ATS is the entire system of adjustments developed for the intention of managing associations among states in the Antarctic. The main goal of the ATS is to guarantee "in the affair of all humankind that Antarctica shall proceed always to be practised completely for peaceful objectives and shall not become the view or gadget of universal disharmony.
Answer:
The correct answer is "Antarctic Treaty System"
Explanation:
The Antarctic treaty system signed the first arms control agreement. It bans any form of military agreement on the Antarctic, and promotes free scientific investigation. The treaty was signed by 12 countries during the era of the cold war. The only use of military is for peaceful purposes and scientific investigations. It promotes free exchange of scientific knowledge and personnel.
How does the shape of a molecule factor into its molecular polarity?
A student is told that both energy and mass must be conserved in every chemical reaction. She measures the mass of Hydrochloric acid and a zinc strip separately. She then places the zinc strip into the acid and bubbles form as the zinc looks like it disappears. The combined mass afterward is less than the original.
Answer:
Explanation:
When we react Hydrochlorid Acid with zinc we have the following reaction:
2HCl(aq) + Zn(s) --> ZnCl2(aq) + H2(g)
The hydrogen gas formed is lost to the environment, so we can affirme that in the start we have the mass for all the H, Cl and Zn atoms in the solution, but after the reaction occurs, we have only the mass for the Cl and Zn atoms.
That's why the mass is less than the original.
The law that the student was told is only applied to closed environments.
Predict the bond present between carbon and hydrogen in polyethylene