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3 years ago

12

What kind of change forms a new substance? A physical change

2 answers:

Stells [14]3 years ago

8 0

Answer:

Chemical change

Explanation: Chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances.

lesya692 [45]3 years ago

4 0

Chemical change ...

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Silicon carbide (SiC) is an important ceramic material made by reacting sand (silicon dioxide, SiO2) with powdered carbon at a h

makkiz [27]

Answer:

Percent yield of SiC is 77.0%.

Explanation:

Balanced reaction: $SiO_{2}+3C\rightarrow SiC+2CO$

Molar mass of SiC = 40.11 g/mol

Molar mass of $SiO_{2}$ = 60.08 g/mol

So, 100.0 kg of $SiO_{2}$ = $\frac{100.0\times 10^{3}}{60.08}$ moles of $SiO_{2}$ = 1664 moles of $SiO_{2}$

According to balanced equation, 1 mol of $SiO_{2}$ produces 1 mol of SiC

Therefore, 1664 moles of $SiO_{2}$ produce 1664 moles of SiC

Mass of 1664 moles of SiC = $(1664\times 40.11)g$ = 66743g = 66.74 kg (4 sig. fig.)

Percent yield of SiC = [(actual yield of SiC)/(theoretical yield of SiC)] $\times 100$ %

= $\frac{51.4kg}{66.74kg}\times 100$ %

= 77.0%

4 0

3 years ago

Misha Larkins [42]

<span>density is defined as mass per volume.. so 94 mL makes no sense.</span>

7 0

3 years ago

The energy of a photon needed to cause ejection of an electron from a photoemissive metal is expressed as the sum of the binding

slega [8]

Answer:

$Binding\ energy=43.43\times 10^{-20}\ J$

Explanation:

Using the expression for the photoelectric effect as:

$E=h\nu_0+\frac {1}{2}\times m\times v^2$

Also, $E=\frac {h\times c}{\lambda}$

$\nu_0=\frac {c}{\lambda_0}$

Applying the equation as:

$\frac {h\times c}{\lambda}=\frac {hc}{\lambda_0}+\frac {1}{2}\times m\times v^2$

Where,

h is Plank's constant having value $6.626\times 10^{-34}\ Js$

c is the speed of light having value $3\times 10^8\ m/s$

$\lambda$ is the wavelength of the light being bombarded

Given, $\lambda=4.00\times 10^{-7}\ m$

$\frac {hc}{\lambda_0}$ is the binding energy or threshold energy

$\frac {1}{2}\times m\times v^2$ is the kinetic energy of the electron emitted. = $6.26\times 10^{-20}\ J$

Thus, applying values as:

$\frac{h\times c}{\lambda}=Binding\ Energy+Kinetic\ Energy$

$\frac{6.626\times 10^{-34}\times 3\times 10^8}{4.00\times 10^{-7}}\ J=Binding\ Energy+6.26\times 10^{-20}\ J$

$\frac{19.878}{10^{19}\times \:4}\ J=Binding\ Energy+6.26\times 10^{-20}\ J$

$49.69\times 10^{-20}\ J=Binding\ Energy+6.26\times 10^{-20}\ J$

$Binding\ energy=43.43\times 10^{-20}\ J$

5 0

3 years ago

Determining wether the molecule is polar or non polar

Rainbow [258]

Answer:

1) polar

2)polar (not too sure about this one)

3)nonpolar

7 0

3 years ago

Which question cannot be answered by science? (4 points)

disa [49]

Answer:

i think one of them cannot be answred by science

5 0

3 years ago

Read 2 more answers