Find the moles in 0.0023 of Co, at STP:

An unknown insoluble substance displaced the water shown. It's mass is indicated on the triple beam balance. Mass = A. 694 B. 69

vodka [1.7K]

Answer:

D. 693.8.

Explanation:

The first scale of the triple beam balance indicate that the mass is 600.

The second scale of the triple beam balance indicate that the mass is 690.

The third scale of the triple beam balance indicate that the mass is higher that 693.5 and the scale is near but lower than 694, so the mass = 693.8.c

3 0

3 years ago

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Can someone please explain this to me? I need help

Vladimir [108]

Answer:

The order would be: X-Rays, Visible Light, and Infrared Waves.

X-Rays have the shortest wavelength out of all three, then Visible Light, and Infrared Waves have the longest wavelength of the three.

Explanation:

So basically, the LONGER the wavelength, the lower the energy. and the SHORTER the wavelength, the higher the energy. For example, Radio waves are the WEAKEST out of all the types of waves because they have the LONGEST wavelengths. Gamma Rays are the STRONGEST out of all the types of waves because they have the SHORTEST wavelengths. So Radio Waves have the lowest energy, and Gamma Rays have the highest energy.

Here is a list of all the types of waves in order from shortest wavelength to longest wavelengths:

Gamma Rays (Shortest Wavelengths, High Energy), then X-Rays would be the second strongest, then Ultraviolet waves, then Visible Light, then Infrared waves, then Microwaves, and lastly Radio Waves (Longest Wavelengths, Low Energy).

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3 years ago

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If you add a neutron to an atom how does it change ?

Kobotan [32]

Answer:

Its atomic mass increases by 1

An isotope of that element is fotmed with mass differences by 1

Explanation:

7 0

2 years ago

Gallium is produced by the electrolysis of a solution made by dissolving gallium oxide in concentrated NaOH ( aq ) . Calculate t

Sedbober [7]

Answer:

Approximately $6.30\times 10^{-3}\;\rm mol$ .

Explanation:

The gallium here is likely to be produced from a $\rm NaGaO_2\, (aq)$ solution using electrolysis. However, the problem did not provide a chemical equation for that process. How many electrons will it take to produce one mole of gallium?

Note the Roman Numeral " $\mathtt{(III)}$ " next to $\rm Ga$ . This numeral indicates that the oxidation state of the gallium in this solution is equal to $+3$ . In other words, each gallium atom is three electrons short from being neutral. It would take three electrons to reduce one of these atoms to its neutral, metallic state in the form of $\rm Ga\, (s)$ .

As a result, it would take three moles of electrons to deposit one mole of gallium atoms from this gallium $\mathtt{(III)}$ solution.

How many electrons are supplied? Start by finding the charge on all the electrons in the unit coulomb. Make sure all values are in their standard units.

$t = \rm 80.0\; min = 80.0\; min \times 60\;s \cdot min^{-1} = 4800\; s$ .

$Q = I \cdot t = \rm 0.380 \; A \times 4800 \; s = 1.824\times 10^3\; C$ .

Calculate the number of electrons in moles using the Faraday's constant. This constant gives the size of the charge (in coulombs) on each mole of electrons.

$\begin{aligned} n(\text{electrons}) &= \frac{Q}{F} \cr &= \rm \dfrac{1.824\times 10^3\; C}{96485.332\; C \cdot mol^{-1}}\cr &\approx \rm 1.89\times 10^{-2}\; mol \end{aligned}$ .

It takes three moles of electrons to deposit one mole of gallium atoms $\rm Ga\, (s)$ . As a result, $\rm 1.89\times 10^{-2}\; mol$ of electrons would deposit $\displaystyle \rm \frac{1}{3}\times 1.89\times 10^{-2}\; mol \approx 6.30\times 10^{-3}\; mol$ of gallium atoms $\rm Ga\, (s)$ .

8 0

3 years ago

Consider the following weak acids and their Ka values: Acetic Acid Ka = 1.8×10^−5 Phosphoric Acid Ka = 7.5×10^−3 Hypochlorous Ac

vfiekz [6]

Answer:

a. Phosphoric Acid

b. Acetic Acid

c. Hypochlorous Acid

Explanation:

A buffer works when the pH of this one is in pKa ± 1. That means, to find which buffer system works in some pH you need to find pKa:

pKa = -log Ka

pKa Acetic acid:

-log1.8x10⁻⁵ = 4.74

pKa phosphoric acid:

-log7.5x10⁻³ = 2.12

pKa hypochlorous acid:

-log3.5x10⁻⁸ = 7.46

a. For a pH of 2.8 the best choice is phophoric acid because its effective range is: 1.12 - 3.12 and 2.8 is between these values.

b. pH 4.5. Acetic acid. effective between pH's 3.74 - 5.74

c. pH 7.5. Hypochlorous acid that works between 6.46 and 8.46

7 0

3 years ago