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3 years ago

A substance is melting, so it is transitioning from solid to liquid. What kind of change is this?

Chemistry

2 answers:

Nostrana [21]3 years ago

8 0

Answer:

chemical or physical i dont know for sure i kniw i have learned this juat cant rember

rewona [7]3 years ago

5 0

Answer:

Your answer will be: Physical

Explanation:

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2H2 + O2 --> 2 H2O + How many moles of oxygen is required to produce 13.3 moles of water?

LenKa [72]

Answer:

Explanation:

Let the number of moles of oxygen = x

2H2 + O2 --> 2 H2O

x 13.3

Since the balance number for oxygen is 1 and the balance number for water is 2, you must set up a proportion. (Those balance numbers represent the number of moles).

1/x = 2 / 13.3 Cross Multiply

2*x = 13.3 Divide both sides by 2

2x/2 = 13.3/2

x = 6.65

You need 6.65 moles of oxygen.

8 0

2 years ago

why a gas, at constant pressure, increases greatly in volume when it is gently heated but a solid does not

11Alexandr11 [23.1K]

Explanation:

This is because gas particles are free to move as they are not held in place by strong molecular forces while particles in a solid are

8 0

3 years ago

5. Before vehicle emissions were well-regulated CO emissions were 66 g/mile. Assume this emission rate applies for an airshed. T

Aleks [24]

Answer:CALINE4 Model and Geographical Information System were used for

the present study to predict the CO concentrations and prepare thematic

maps for the study area.

CALINE4 is a latest model that predicts the concentration of carbon

monoxide impacts near the roadways. The California Department of

Transformation (CALTRANS) developed the model and its purpose is to help

planners protect public health from the adverse effects of carbon monoxide.

The model predictions along with the aid of GIS based model help to arrive at

air shed levels of carbon monoxide. CALINE4 is a simple line source

Gaussian plume dispersion model. The user defines the proposed roadway

geometry, worst-case meteorological parameters, anticipated traffic volumes

and receptor positions to predict the concentrations of pollutant.

CALINE4 is graphical with windows based user interface, designed to

ease data entry and increase the online help capabilities. The model was

developed for predicting the concentrations of relatively inert pollutants such

as carbon monoxide and it is now used for several other pollutants like NO2

and SPM. The model is based on fine tuned Gaussian diffusion equation and

it employs mixing zone concept to characterize the pollutant dispersion over

the roadways. Given the exhaust emission concentrations, meteorology and

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Explanation:

4 0

3 years ago

What is the final concentration of cl- ion when 250 ml of 0.20 m cacl2 solution is mixed with 250 ml of 0.40 m kcl solution? (as

serious [3.7K]

CaCl2 and KCl are both salts which dissociate in water when dissolved. Assuming that the dissolution of the two salts are 100 percent, the half reactions are:

CaCl2 ---> Ca2+ + 2 Cl-

KCl ---> K+ + Cl-

Therefore the total Cl- ion concentration would be coming from both salts. First, we calculate the Cl- from each salt by using stoichiometric ratio:

Cl- from CaCl2 = (0.2 moles CaCl2/ L) (0.25 L) (2 moles Cl / 1 mole CaCl2)

Cl- from CaCl2 = 0.1 moles

Cl- from KCl = (0.4 moles KCl/ L) (0.25 L) (1 mole Cl / 1 mole KCl)

Cl- from KCl = 0.1 moles

Therefore the final concentration of Cl- in the solution mixture is:

Cl- = (0.1 moles + 0.1 moles) / (0.25 L + 0.25 L)

Cl- = 0.2 moles / 0.5 moles

Cl- = 0.4 moles (ANSWER)

6 0

3 years ago

To find the atomic mass of a particular atom you need to know

Andreyy89

You just need the number of protons and number of neutrons as the mass of eelctrons is negligible

5 0

3 years ago

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