## Search found 108 matches

Sun Oct 13, 2019 8:04 pm
Forum: Properties of Electrons
Topic: 1B 15C
Replies: 1
Views: 30

### 1B 15C

The velocity of an electron that is emitted from a metallic surface by a photon is 3.6 x 10^3 km/s. (c) What is the wavelength of the radiation that caused photoejection of the electron? I was able to find the wavelength of the ejected electron and the energy required to remove it from the metal. Ho...
Sun Oct 13, 2019 7:46 pm
Forum: Properties of Electrons
Topic: kinetic energy equation help
Replies: 2
Views: 36

### Re: kinetic energy equation help

The mass of the electron is 9.10938 x 10^-31 kg, and it will always be the same. You aren't actually "solving" for the mass of the electron, but it's something that is given in the textbook.
Sun Oct 13, 2019 7:39 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Uncertainty Principle Module 18
Replies: 1
Views: 39

### Heisenberg Uncertainty Principle Module 18

The hydrogen atom has a radius of approximately 0.05 nm. Assume that we know the position of an electron to an accuracy of 1 % of the hydrogen radius, calculate the uncertainty in the speed of the electron using the Heisenberg uncertainty principle. Comment on your value obtained. If the position of...
Sat Oct 05, 2019 2:41 pm
Forum: Significant Figures
Topic: Sig Figs When Adding and Subtracting
Replies: 3
Views: 64

### Re: Sig Figs When Adding and Subtracting

When adding or subtracting, you keep the significant figures for the least amount of places after the decimal point. For example, 150.0 + 0.507 would be 150.5. This is because 150.0 has one place after the decimal point, while 0.507 has 3. So, you keep the least number of places after the decimal in...
Sat Oct 05, 2019 2:36 pm
Forum: Limiting Reactant Calculations
Topic: M 15B
Replies: 1
Views: 59

### Re: M 15B

For problem M15 part B, how would you determine the mass of aluminum chloride that can be produced by the reactants? My answer is different from the one in the odd numbered examples solutions and I don't know why. How I solved this part was using the mass given for each of the reactants to find the ...
Sat Oct 05, 2019 2:28 pm
Forum: Empirical & Molecular Formulas
Topic: M 15
Replies: 1
Views: 48

### Re: M 15

Aluminum metal would just be Al(s). Chlorine gas is Cl2(g) becaue it is a diatomic molecule. So, the equation would be Al(s) + Cl2(g) --> AlCl3(s). You can find out the product of aluminum and chlorine gas by crossing their charges to get the subscripts since Al has a 3+ charge and Cl has a -1 charg...
Fri Oct 04, 2019 2:58 am
Forum: SI Units, Unit Conversions
Topic: Homework: L35
Replies: 2
Views: 73

### Homework: L35

Sodium bromide, NaBr, which is used to produce AgBr for use in photographic film, can itself be prepared as follows: Fe + Br2 --> FeBr2 FeBr2 + Br2 --> Fe3Br8 FeBr2 + Na2CO3 --> NaBr + CO2 + Fe3O4 What mass of iron, in kilograms, is needed to produce 2.50 t of NaBr? Note that these equations must fi...
Fri Oct 04, 2019 2:26 am
Forum: Molarity, Solutions, Dilutions
Topic: G17 Part B
Replies: 1
Views: 52

### G17 Part B

Determine the mass of CuSO4 5H2O (copper(II) sulfate pentahydrate) that must be used to prepare 250 mL of 0.20 m CuSO4(aq). Hello, I am having trouble with part b! I found the amount of moles of just anhydrous copper (II) sulfate using the molarity formula. However, I don't understand how the moles ...