Why can an element be identified by its properties?

Hydrogen reacts with oxygen to create water. Write the balanced equation first. If there are 4.0 moles

stealth61 [152]

1 mole of oxygen is required

8 0

3 years ago

Name two uses for seismometers

NNADVOKAT [17]

Earthquakes and volcanic eruption

8 0

3 years ago

A student measures the absorbance of a sample of red dye #3 using a spectrophotometer. If the absorbance is measured as 0.468, w

Gre4nikov [31]

Answer:

5.88 μM is the concentration of red dye in the sample.

Explanation:

Absorbance is defined s capacity of a substance to absorb a light of a specified wavelength.It is calculated by using Beer-Lambert Law:

$A=\epsilon lc$

A = absorbance

$\epsilon$ = Molar absorptivity

c = concentration

l = Length of the solution through which light passes

Given, A = 0.468, l = d = 1.00 cm,c = ?

$\epsilon =7.96\times 10^4 M^{-1} cm^{-1}$

$A=\epsilon lc$

$0.468=7.96\times 10^4 M^{-1} cm^{-1}\times 1.00 cm\times c$

$c=5.8793\times 10^{-6} mol/L=5.8793 mol/(\mu L)\approx 5.88mol/(\mu L)$

( $1 L= 1,000,000 \mu L$ )

5.88 μM is the concentration of red dye in the sample.

5 0

4 years ago

What is the energy required to change a spherical drop of water to five smaller spherical drops of equal size? At room temperatu

pav-90 [236]

This is a straightforward question related to the surface energy of the droplet. 

You know the surface area of a sphere is 4π r² and its volume is (4/3) π r³. 

With a diameter of 1.4 mm you have an original droplet with a radius of 0.7 mm so the surface area is roughly 6.16 mm² (0.00000616 m²) and the volume is roughly 1.438 mm³. 

The total surface energy of the original droplet is 0.00000616 * 72 ~ 0.00044 mJ 

The five smaller droplets need to have the same volume as the original. Therefore 

5 V = 1.438 mm³ so the volume of one of the smaller spheres is 1.438/5 = 0.287 mm³. 

Since this smaller volume still has the volume (4/3) π r³ then r = cube_root(0.287/(4/3) π) = cube_root(4.39) = 0.4 mm. 

Each of the smaller droplets has a surface area of 4π r² = 2 mm² or 0.0000002 m². 

The surface energy of the 5 smaller droplets is then 5 * 0.000002 * 72.0 = 0.00072 mJ 
From this radius the surface energy of all smaller droplets is 0.00072 and the difference in energy is 0.00072- 0.00044 mJ = 0.00028 mJ. 

Therefore you need roughly 0.00028 mJ or 0.28 µJ of energy to change a spherical droplet of water of diameter 1.4 mm into 5 identical smaller droplets.

3 0

3 years ago

In which location would an ocean ridge most likely be located

Nastasia [14]

An ocean ridge is an underwater mountain system which is the result of tectonic plate movement. Its formation involves two processes: ridge-push and slab pull. The former occurs when the growing bulk of the ridge pushes the rest of the tectonic plate away from the ridge. Oftentimes, they go towards a subduction zone. In this zone, the latter, which is the slab pull comes into effect. This is the weight of the tectonic plate subducted or pulled down below the overying plate tagging along the rest of the plate behind it.

They are generally located halfway between two continents.

7 0

3 years ago