48 Answered Questions for the topic Chemistry HelpNeeded

09/28/18

what does it mean when we say peptide 35 or peptide2 is that the location of the amino acid
what does it mean when we say peptide 35 or peptide2is that the location of the amino acid
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09/08/18

Hydrchloric acids
When calcium carbonate is added to hydrochloric acid, calcium chloride, carbon dioxide, and water are produced.  CaCO3 + 2HCl = CaCl2 (aq) + H2O + CO2 A.)How many grams of calcium chloride will be... more
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08/22/18

A sample of MgCO3•3H20 (magnesium carbonate trihydrate) is heated until 40.37 grams of water are released. How many grams did the original hydrate weigh?
MgCO3•3H2O
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08/22/18

Neutralization
What volume (in ml) of 0.395 mol/L Calcium Hydroxide, ca(OH)2(aq) is needed to completely netralize 22.8 ml of 0.343mol/L phosphoric acid, H3PO4(aq)?   3CA(OH)2 + 2H3PO4 = Ca3(PO4)2 + 6H20
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08/21/18

Check for my answers for me thank you
A 250 mL sample of gas was initially at a pressure of 101 kPa at 80°C. If the volume decreases to 100 mL at 50°C, how would you calculate the new pressure?I would calculate it by doing this:101 kPa... more
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08/21/18

A sample of gas at a pressure of 3.0 atm was compressed from 6.00 L to 3.00 L at constant temperature.
After the compression, what will the pressure of the gas be?     
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08/21/18

At constant temperature and pressure, 1.25 mol of hydrogen gas occupies 28 L at STP.
What amount of hydrogen gas must be removed from the volume to become 11.2 L at STP?   a) 0.13 mol b) 0.25 mol c) 0.50 mol d) 0.75 mol e) 1.00 mol   Is it c) I'm unsure 
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08/21/18

Use the combined gas law
The pressure of a gas is decreased from 400 kPa to 200 kPa &the temperature is raised from 200 K to 300 K. The volume of the gas will:a) Decrease by halfb) Remain the samec) Increase by two... more
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08/21/18

What volume of oxygen gas at STP is required to react with 10g of potassium metal according to the following equation?
2K(s)+O2(g) = K2O(s)   a) 5.8 L b) 8.7 L c) 1.5 L d) 11.5 L  e) 2.9 L   My predication is b) I'm unsure 
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08/17/18

CHEM AP PLZ HELP
Can a concentrated basic solution be a weak base?   A: Yes  B: No C: Yes, but only if the base is a hydroxide  D: yes, but only at high temperatures  E: Yes, but only if the base contains... more
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08/17/18

Marble is made primarily of calcium carbonate.
When calcium carbonate reacts with hydrogen chloride, it reacts to form calcium chloride, carbon dioxide, and water. If this reaction occurs with 51.6% yield, what mass of carbon dioxide will be... more
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08/17/18

What volume (in mL) of 0.348 mol/L calcium hydroxide. Ca(OH)2 (aq), is needed to completely neutralize 38.2mL of 0.432 mol/L phosphoric acid, H3PO4 (aq)
Please show all your work! 
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08/17/18

A commercial refrigeration unit accidentally releases (6.42*10^1) mL of ammonia gas at SATP. Determine the mass and number of molecules of ammonia gas released.
Please show all your work.    Note: your answer is assumed to be reduced to the highest power possible 
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08/17/18

A 30.00 ml gas syringe was at a pressure of 100.0 kPa at 30.0°c
A 30.00 ml gas syringe was at a pressure of 100.0 kPa at 30.0°c. On the following day, the temperature dropped to 26.0°c and the new volume was 23.1 mL. What was the atmospheric pressure on this day?
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08/11/18

in the manufacture of potassium permanganate a solution containing manganate ion is oxidized by chlorine. Would bromine or iodine be as good?
in the manufacture of potassium permanganate a solution containing manganate ion is oxidized by chlorine. Would bromine or iodine be as good?
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08/08/18

aqueous potassium chloride will react with which of the following?
aqueous potassium chloride will react with which of the following? A. calcium nitrate B. sodium bromide C.lead nitrate D.barium nitrate E. sodium chloride   I know the answer is lead nitrate... more
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07/20/18

Question about how significant digits work in chemistry.
I'm doing my online chemistry summer class and significant digits are included, of course. But I'm confused about them because everything I believe is being contradicted. Here's what I... more
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07/03/18

what can i say for the conclusion armspan vs height with the 0.98 positive correlation coefficient
I need help with this question
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06/14/18

evaluate the accuracy of the measurements made, contrasting them with wet techniques, where eg. (determination of Cu2+ concentration by titration and
by colourimetery
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05/16/18

Which of the following is the weakest acid?
A.  HF (KA for HF is 7.2 x 10-4) B.  H3BO3 (Ka for H3BO3 is 5.4 x 10 -10) C.  HCNO (ka for HCNO is 2 x 10-4) D.  HCN (ka for HCN is 4.9 x 10-10)
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05/16/18

write chemical, complete ionic and net ionic equations for the reaction between CaCl2 and NaCO3
I cannot figure it out, although i think that it has something to do with a double replacement reaction.
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05/14/18

iron crystallizes in a body-centered unit cell with an edge length of 287 pm. what is the atomic radius of iron
What is the atomic radius of iron? Show all steps please! 
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05/12/18

When KCl dissolves in water...
The answer is the K+ ions are attracted to the partially negative oxygen atoms of the water molecule. My question is, is that why does it do this? Would someone be able to explain why this happens... more
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04/30/18

How do you balance this equation : CuFeS2+O2+SiO2=Cu2S+FeSiO3+SO2+ Cu2O
I'm not able to balance the Cu and O's, would someone please be able to explain to me how you balance this equation? Any help would be much appreciated. Thank you
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04/29/18

Chemistry: Stoichometry
A 1.00 gram sample of potassium bicarbonate is decomposed by heating. If the resulting potassium carbonate weighs 0.725 grams and the calculated yield is 0.776 grams, what is the percent yield?
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