If your question is part of your high school or college/university homework, please use this tag. It signifies that instead of a direct answer, care should be taken to explaining the steps to the solution, preferably sticking to just giving helpful, conceptual hints. This tag may be applied to ...

learn more… | top users | synonyms

1
vote
0answers
10 views

Is this correct ? Are my calculations correct?

what is the molecular formula of a compound containing only carbon and hydrogen if combustion of 1.05 g of the compound produces 3.30 g CO2 and 1.35 g H2O and its molar mass is about 70 g ?
0
votes
0answers
3 views

Filtration of chloride in gravimetric analysis

The final filtration of a chloride gravimetric analysis allows some very fine precipitate through the filter into the filtrate. Allowing the precipitate to stand longer (to "digest") may have reduced ...
0
votes
0answers
24 views

Outermost electronic configuration of f block elements

I have a doubt regarding the general outermost electronic configuration of f block elements. Why is it (n-2)f^(1-14)(n-1)d^(0-1)ns^2. The only exception i thought to this formula was thorium 5f^(0) ...
0
votes
1answer
16 views

Which reactant to use to calculate yield?

A chemist mixes 24.0 g $H_2$ with 8.0 g $N_2$. Assuming the reaction goes to completion, which reactant should she use to calculate the yield? $3H_2 + N_2 \implies 2NH_3$ I believe it should be ...
0
votes
0answers
7 views

Gravimetric Analysis of phosphate while precipitating magneisum ammonium

When precipitating magnesium ammonium phosphate in the gravimetric analysis of phosphate, you assume that the percentage of phosphorus in your 2-g sample is about 10%. How many milliliters of ammonia ...
0
votes
0answers
12 views

Gravimetric Analysis

You have a sample of silver alloy and would like to know how much silver is in it. Dissolve the silver sample in nitric acid. Filter to remove any insoluble material. Add an excess of KCl solution, ...
0
votes
0answers
17 views

The space shuttle burns liquid hydrogen and oxygen in the main engine [on hold]

If 102000 kg of liquid hydrogen is carried on particular launch. What mass of liquid oxygen is necessary for all the hydrogen burnt. $$\ce{2H2(g) + O2(g) -> 2H2O}$$
-1
votes
1answer
50 views

Uncertainty / Accuracy Confusion

My simple question is: Let us assume, that the speed is measured within accuracy of 2 percent. When the speed of something is 45, then why do we take uncertainty as 2 percent of 45 and not 98 ...
0
votes
0answers
27 views

When magnesium metal is added to hydrochloric acid the following reaction takes place:

When magnesium metal is added to hydrochloric acid the following reaction takes place: $\ce{Mg(s) + 2HCl(aq) -> MgCl2(aq) + H2(g)}$. What volume of hydrochloric acid of concentration 0.10 mol dm-3 ...
0
votes
0answers
10 views

Which of the following is the most suitable reagent to test for the presence of the iodide ion in an aqueous solution?

Which of the following is the most suitable reagent to test for the presence of the iodide ion in an aqueous solution? Acidified barium chloride solution Acidified silver nitrate solution Aqueous ...
0
votes
1answer
29 views

Which of the following does not represent a possible reaction?

Which of the following does not represent a possible reaction? A.Chlorine + sodium iodide → potassium chloride and iodine B.fluorine + sodium chloride → potassium fluoride and chlorine C.bromine + ...
0
votes
0answers
9 views

Which of the following methods could be used to remove yeast from fermented sugar solution?

Which of the following methods could be used to remove yeast from fermented sugar solution? centrifuge; crystallisation; Fractional distillation; chromatography; Filtration I'm not sure wich one ...
-1
votes
0answers
23 views

percent composition of compounds [on hold]

without doing detailed calculation , estimate whether the percent composition by mass of $\ce{Sr}$ is greater than or smaller than that of $\ce{O}$ is strontium nitrate $\ce{Sr(NO3)2}$
0
votes
1answer
16 views

Calculating collision diameter with viscosity, but not having the mass given

I've got a homework question i'm stumped on. The viscosity of the ethylene gas was measured at $99.8*10^{-7} \textrm{ N s m}^{-2}$ at $288 \textrm {K}$. Calculate the collision diameter in ...
0
votes
1answer
23 views

estimating magnitude of percent and absolute error

Can someone at least give me a hint to push me in the right direction of how to estimate magnitude of the absolute and percent errors when using a smaller amount in mL of a substance for a lab ...
1
vote
2answers
76 views

can't predict IUPAC name of this compound, seems i am missing some concept of nomenclature here

I am talking by keeping the below diagram in my vision. This compound on elaborate elongation would result in this structure. But is the below given numbering correct? I am just dubious that ...
3
votes
1answer
127 views

Symmetry labels for orbitals

What are the symmetry labels for the p and d orbitals of $\ce {[PtCl4]^{2-}}$ ? I understand the concept of symmetry labels for molecules. some explanation of how it applies to orbitals would be ...
1
vote
1answer
108 views

How many Au atoms can be extracted from .250L of seawater?

Gold is present in seawater to the extent of 0.15mg/ton. Assume the density of seawater is 1.03g/ml and determine how many gold atoms could be extracted from 0.250L of seawater. (1 ton=2000lbs, ...
0
votes
0answers
23 views

45.9 gram sample of borane (a compound containing only boron and hydrogen) and is 85.63% boron. What's the mass of hydrogen in this sample?

45.9 gram sample of borane (a compound containing only boron and hydrogen) that's 85.63% boron. What's the mass of hydrogen in this sample? I was just going to take 45.9 grams and multiply by .1437 ...
1
vote
1answer
28 views

What are the other definitions of redox reactions besides the gain or donation of oxygen?

As my teacher told us, oxidation is the gaining of oxygen and reduction is the donation of oxygen. In my reference book there are other definitions of this reaction. So please give me some alternate ...
-2
votes
1answer
35 views

Battery acid density of 1.285 grams per cubic centimeter

Battery acid has a density of 1.285 grams per cubic centimeter and contains 38% by weight H2SO4, how many grams of pure H2SO4 are contained in a liter of battery acid? I just took 1.285 times .38 and ...
-1
votes
1answer
30 views

A solution of iron (III) chloride contains 0.9mol/L chloride ions. Calculate the mass of solute needed to make 1L [on hold]

I have the following assignment: A solution of iron (III) chloride contains 0.9mol/L chloride ions. Calculate the mass of solute needed to make 1L I got the formula: $\ce{Fe^{3+} + 3Cl^{-} -> ...
0
votes
2answers
27 views

Using the Law of Constant Composition: Magnesium and Oxygen Mass

What masses of magnesium and oxygen must be combined to make exactly 2.000 g of magnesium oxide? Magnesium's atomic weight is 24.305 and Oxygen's atomic weight is 15.999. Do I simply add the two ...
0
votes
1answer
16 views

Calculate the volume occupied at rtp by 12.5 moles of SO2 gas

I have been trying really hard to do this but I'm really lost. I don't know what to multiply by what to get the right answer.
3
votes
1answer
30 views

Finding the equilibrium constant Kₚ, when temperature is given

At $1000~\mathrm{K}$, $K_p = 1.85$ for the reaction. $$\ce{SO_2 + \frac{1}{2}O_2 <=> SO_3}$$ What is the value of $K_p$ for the reaction $$\ce{SO_3 <=> SO_2 + ...
0
votes
2answers
67 views

Derivation of a formula

I have a formula for finding the final temperature in an irreversible adiabatic expansion. $$T_2=\left[\frac{C_v+(\frac{P_2}{P_1})}{C_p}\right]T_1$$ where $T_1$ is the initial temperature. $C_v$ and ...
0
votes
1answer
40 views

How does K2Cr2O7 become Cr2O7 2-

This might be a basic question,But I have no idea how it works. How does K2Cr2O7 become Cr2O7 2- ? Any information regarding this would be really helpful to me.
3
votes
2answers
73 views

Absolute and relative uncertainty problems

My professor, for whatever reason, assigned problems for us to do without previously teaching us how to perform the problems which were given. If anyone happens to know how to do this and can show me, ...
1
vote
1answer
34 views

How many grams of acetic acid are present in 2.80L of this vinegar?

A vinegar sample is found to have a density of $1.006 \mathrm{\frac{g}{mL}}$ and to contain $8.7\%$ acetic acid by mass. I multiplied $(\frac{1.006~\mathrm{g}}{\mathrm{ml}})\cdot ...
0
votes
1answer
80 views

Answer Conversion Problem Numerically in Kilometers Per Hour [closed]

A sprinter set a high school record in track and field, running $200.0~\mathrm{m}$ in $22.0~\mathrm{s}$ . What is the average speed of the sprinter in kilometers per hour? Express the answer ...
0
votes
0answers
29 views

how to calculate the amount of N2 gas needed to displace O2 to 19.5%?

I have 900L of liquid $\ce{N2}$ stored at 500 psi. Using the Gas port of the tank the pressure is dropped to 50 psi to send through a 3/8 inch tube into another regulator to drop the pressure to 10 ...
0
votes
0answers
24 views

Which statement is TRUE? [closed]

If copper and zinc metal electrodes are used in a simple battery cell made by dipping strips of zinc and copper into their salt solutions which statement is TRUE? A. Cu(s) → Cu2+(aq) + 2e occurs on ...
1
vote
3answers
32 views

Copper is a metallic element, so it is likely to be?

Copper is a metallic element, so it is likely to be? A. Poor conductor of electricity B. A substance with a low melting point C. Malleable D. Poor conductor of heat E. An element ...
1
vote
1answer
34 views

Magnesium powder mixed with CuSO4 solution

$\ce{Mg}$ powder is stirred into $\ce{CuSO4}$, what is the balanced molecular equation for this reaction ? I have $\ce{Mg + CuSO4 -> Mg2SO4 + Cu}$. Also, is the ionic equation the same as the net ...
-2
votes
0answers
31 views

How to determine the molecular mass of a solute using Raoult's law? [closed]

A solution is prepared from 75.0 g of a nonvolatile, non dissociating solute and 85.0 g of water. The vapor pressure of the solution at 60°C is 132 torr. The vapor pressure of water at 60°C is 150. ...
1
vote
1answer
32 views

Potassium Atom can act as reducing agent, yet ion cannot?

I am currently looking through a revision sheet, however it has caught me on a question 'Explain why a potassium atom can act as a reducing agent yet a potassium ion cannot'. I have done brief ...
4
votes
3answers
2k views

Would equal masses of gold and copper result in the same volume change if added to water?

Would equal masses of gold and copper result in the same volume change if added to water? Density of gold: $19.3~\mathrm{g/mL}$ Density of copper: $8.96~\mathrm{g/mL}$ I was thinking the ...
4
votes
1answer
50 views

Correlation between the virial coefficients and a & b in the corresponding Van Der Waals equation of state

I don't know where to begin with this question. A function f(x) can be expressed as a special power series called the Taylor expansion. The common expansion is $(1-x)^{-1}=1+x+x^2$ Note that the ...
0
votes
1answer
22 views

Why is the water column empty in ICE table

In the ICE table pure solids and liquids have a value of one in the equilibrium expression but when we create an ICE table, why is the $\ce{H_{2}O}$ column empty? Should it not have a value of one?
1
vote
1answer
24 views

how to determine timescale with characterization methods?

There are as classified in the Atkins textbook 4 different timescales on material characterization: a)Time during which a quantum of radiation or a particle can interact with a molecule. b)Lifetime of ...
1
vote
1answer
34 views

Approximately what fraction of composition of wood's volume is submerged?

Approximately what fraction of its volume is submerged when a $1.00~\mathrm{kg}$ block of wood $(d= 0.68~\mathrm{g/cm^3})$ floats on water? I plugged the values according to the density formula, ...
0
votes
1answer
61 views

Rates of reaction

Assume a reaction is of second order kinetics and that the rate constant is k. The differential rate equation is given by: A+B->Products -dCa/dt = kCaCb Show that the general expression of ...
1
vote
1answer
24 views

Calculating amount of ice required for heat loss

Question: Given $400.0\ \mathrm{g}$ of hot tea at $80.0 °\mathrm{C}$, what mass of ice at $0 °\mathrm{C}$ must be added to obtain iced tea at $10.0 °\mathrm{C}$? The specific heat of the tea ...
4
votes
1answer
26 views

Determining redox half-reactions of single displacement reactions

For the following double displacement half reaction, the half reactions can be determined easily using the oxidation numbers. $$\ce{MnO_{4(aq)}^{-} + IO_{3(aq)}^- -> MnO_{2(s)} + IO_{4(aq)}^-}$$ We ...
1
vote
0answers
46 views

My question is regarding chemical calculations [closed]

If 25.15g $\ce{KClO3}$ is heated at 750 degrees Celsius and decomposed; how much oxygen will we get from it at 1.25 atm (pressure) and 50 degrees Celsius?
1
vote
3answers
59 views

What would the Electronic Configuration of Ru²⁺ be?

I'm doing homework for Inorganic Chemistry, and I am a little confused. The Question is: What is the electronic configuration of $\ce{Ru^{2+}}$? If I were to remove from the highest energy ...
2
votes
2answers
68 views

Atomic Mass of ¹²C before 1961

Question: Prior to 1961, the atomic mass unit was defined as 1/16 the mass of the atomic mass of oxygen; that is, the atomic mass of oxygen was defined as exactly 16 amu. What was the mass ...
2
votes
1answer
69 views

How to convert cm² to km²?

I have a problem that says "a small hole is $20.7~\mathrm{cm^2}$ wide. What is the area in $\mathrm{km^2}$." I started doing it like this: $20.7~\mathrm{cm^2} \cdot 0.01~\mathrm{m^2} / ...
3
votes
3answers
97 views

Determining exponents in a rate law with different data

Here is the experimental data: Note all concentrations are the initial amounts \begin{array}{cccc} \text{Experiment} & \ce{[C_{2}H_{4}Br_{2}]} &\ce{[I^{-}]} & \text{Initial rate of ...
5
votes
3answers
563 views

During a phase change in matter, why doesn't the temperature change?

I was working on something in school and came across the question: "Why do you think the temperature does not change much during a phase change?" I'm really not sure why this happens in matter ...