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dalvyx [7]
3 years ago
11

What is chalk made of?

Chemistry
2 answers:
aksik [14]3 years ago
7 0
I think it is calcium carbonate, from sedimentary rocks and such
skelet666 [1.2K]3 years ago
6 0
Calcium carbonate
---------------------------
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What negative effects can increase tropospheric ozone level hav on humans
anzhelika [568]
If the O-Zone Tropo increased to a point, like it has, it can cause a huge variety of health problems and even death! Some of the problems include, but are not limited to: Asthma, E<span>mphysema, Chest Pain, Inflamed Lungs and Lung Scarring from tissue damage. </span>
5 0
3 years ago
10. Haley the hummingbird can fly from a pansy flower to a hibiscus flower 20 meters away in 5 seconds.
Dennis_Churaev [7]

Answer:

4

Explanation:

Speed=Distance/time, so 20/5 divide time divided by distance. so the answer is 4.

4 0
2 years ago
Read 2 more answers
A tank with volume of 2.4 cu ft is filled with Methane to a pressure of 1500 psia at 104 degrees F. Determine the molecular weig
Soloha48 [4]

Explanation:

It is known that equation for ideal gas is as follows.

               PV = nRT

The given data is as follows.

     Pressure, P = 1500 psia,     Temperature, T = 104^{o}F = 104 + 460 = 564 R

     Volume, V = 2.4 cubic ft,      R = 10.73 psia ft^{3}/lb mol R

Also, we know that number of moles is equal to mass divided by molar mass of the gas.

                n = \frac{mass}{\text{molar mass}}

            m = n \times W

                = 0.594 \times 16.04

                = 9.54 lb

Hence, molecular weight of the gas is 9.54 lb.

  • We will calculate the density as follows.

                d = \frac{PM}{RT}

                    = \frac{1500 \times 16.04}{10.73 \times 564}

                    = 3.975 lb/ft^{3}

  • Now, calculate the specific gravity of the gas as follows.

  Specific gravity relative to air = \frac{\text{density of methane}}{\text{density of air}}

                         = \frac{3.975 lb/ft^{3}}{0.0765 lb/ft^{3}}

                         = 51.96

6 0
3 years ago
If an ultraviolet photon has a wavelength of 77.8 nm calculate the energy of one mole ultraviolet photon.
DerKrebs [107]

Answer:

Explanation:

E = (hc)/(λ)

E = (6.624x10^(-27))Js x ((3×10^8)ms^(-1)) /

(77.8x10^(-9)m)

E = 2.55 x 10^(-11) J

7 0
2 years ago
3. If you start with 8x1025 molecules of Cl, and 25 grams of KI, how many grams of KCl would
miskamm [114]

Answer:

Percent yield = 89.1%

Explanation:

Based on the equation:

Cl₂ + 2KI → 2KCl + I₂

<em>1 mole of Cl₂ reacts with 2 moles of KI to produce to moles of KCl</em>

<em />

To solve this quesiton we must find the moles of each reactant in order to find the limiting reactant. With the limiting reactant we can find the moles of KCl and the mass:

<em>Moles Cl₂:</em>

8x10²⁵ molecules * (1mol / 6.022x10²³ molecules) = 133 moles

<em>Moles KI -Molar mass: 166.0028g/mol-</em>

25g * (1mol / 166.0028g) = 0.15 moles

Here, clarely, the KI is the limiting reactant

As 2 moles of KI produce 2 moles of KCl, the moles of KCl produced are 0.15 moles. The theoretical mass is:

0.15 moles * (74.5513g / mol) =

11.2g KCl

Percent yield is: Actual yield (10.0g) / Theoretical yield (11.2g) * 100

<h3>Percent yield = 89.1%</h3>
3 0
3 years ago
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