12/12/19

CHEMISTRY : If 50% of a radioactive element remains after 4000 years, what is the half-life?

If 50% of a radioactive element remains after 4000 years, what is the half-life? please help.
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12/12/19

Na2S2O3+AgBr=NaBr+Na3[Ag(S2O3)]2 How many moles of Na2S2O3 are needed to react completely with 42.7g of AgBr? What is the mass of NaBr that will be produced from 42.7 g of AgBr?
Step by step and where each number came from and clear explanation
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12/12/19

For 12.4g of liquid SO2Cl2 obtained from the reaction of 6.11g of gaseous SO2 and excess gaseous Cl2, calculate the percent yield.

Step by step how to solve and get the percent yield
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12/11/19

If 15g of a metal at 150C with a heat capacity of 0.81 J g/C is added to 100.g of water at 25C at 4.1J/gC, what temperature will the combined system arrive at?
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12/11/19

Chemistry question
How man grams of potassium are required to produce 3.64 g of Hydrogen has, H2?
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12/11/19

Which sample has the fewest number of atoms
A. 24.3g of MagnesiumB. 9.0g of Beryllium C. 5.1g of LithiumD. 12.0g of Carbon
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12/11/19

Carbon-14 dating is often used to find the age of human-era relics. The half-life of Carbon-14 is 5,730 years.
Carbon-14 dating is often used to find the age of human-era relics. The half-life of Carbon-14 is 5,730 years.If it is determined that 3 half lives go by, how many years has that been?Enter your... more
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12/11/19

The decay: 17578Pt→42He+17176Os has a half life of 2.53 seconds.If you originally begin with 158.7 grams of 175Pt, how many grams of 171Os would you have after 7.59 seconds?
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12/11/19

N2(g) +O2(g)=2NO(g) Kc=0.10 at 2000 Celsius Starting with initial concentrations of 0.040 mol/L of N2 and 0.040 mol/L of O2, calculate the equilibrium concentration of NO in mol/L.
having trouble with equilibrium do not seem to get the hang of it.
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12/11/19

How many milliliters of 5.0 M copper(II) sulfate solution must be added to 160 mL of water to achieve a 0.30 M copper(II) Sulfate solution?
I seem to get confused on what to convert to what and how to set up this equation? Step by step how to solve.
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12/11/19

How many moles of CO2 gas are present in a 7.26 L vessel at a pressure of 347 torr and a temperature of 25 °C?
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12/11/19

What is the molar mass of an unknown gas if 0.948 g of the gas occupies a 2.50 L vessel and its temperature and pressure were measured and found to be 65°C and 250. torr, respectively?
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12/11/19

Write a balanced overall reaction given the unbalanced half‑reactions. Rb ⟶ Rb + Mg 2 + ⟶ Mg

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12/11/19

What percent of water should be evaporated to obtain a 0.6 M KOH solution? 
A 0.2 M KOH solution has a volume of 3 L.What percent of water should be evaporated to obtain a 0.6 M KOH solution? 
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12/11/19

What is the pOH of a 5.0 ×10-5 M hydrochloric acid (HCl) solution at 25° C?
What is the pOH of a 5.0 ×10-5 M hydrochloric acid (HCl) solution at 25° C?
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12/11/19

What is the volume of this solution? 
The molarity of a sodium hydroxide solution is 0.2 M. The molar mass of NaOH is 40 g/mol.If 20 g of sodium hydroxide (NaOH) is dissolved in water in this solution, what is the volume of the... more
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12/10/19

How many milliliters of a 0.250 M NaOH solution will be required to completely react with 12.74 mL of 0.250 M H2SO4?
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12/10/19

Explain the relationship of a gas’s pressure to its volume, temperature, and number of particles.
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12/10/19

Explain the chromatographic separation of a mixture of three dyes
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12/10/19

Explain why calcium carbonate is unable to dissolve appreciably in water.
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12/10/19

General Chemistry Math Question 4
Determine the pH at the equivalence point for the titration of 200 mL of 0.0525 M NaCN with 0.0375 M HCl. The Ka for HCN is 4.9 x 10^-10.
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12/10/19

General Chemistry 2 Math Question 3
i. For the reaction below, Kc = 0.66 at a certain temperature. If a reaction flask contains 1.35 M NO2, 1.35 M NO, and 1.25 M O2, will the equilibrium concentration of NO2 be greater than, less... more
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12/10/19

General Chemistry 2 Math Question 2
A voltaic cell was constructed using the following half-reactions: Cu2+(aq) + 2 e-1 " Cu(s) Sn2+(aq) + 2 e-1 " Sn(s) Determine the net cell reaction, the standard cell potential, E0 cell, and ΔG°... more
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12/10/19

General Chemistry 2 Math Question
You need a buffer to maintain a pH of 3.20. How many grams of sodium cyanate (NaOCN) would you need to add to 250 mL of a 0.125 M solution of cyanic acid (HOCN, Ka = 3.5 × 10-4 ) to have the... more
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12/10/19

C4H6(g)+2Cl(g)=C4H6Cl4(l) Calculate the mass of C4H6Cl4 that can be prepared from 35.0g of C4H6 and 105.0g of Cl2?
Not sure where to start. Step by step please
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