Who is credited with creating the first periodic table

Carbon has an atomic number of 6. This means it has 6 protons and 6 electrons. How many valence electrons does carbon have?

Varvara68 [4.7K]

Answer:

4

Explanation:

Carbon configuration- 2,4

Valence electrons means the outershell electrons

That means valence electrons=4

8 0

2 years ago

Balance the following redox equation in acidic solution using the smallest integers possible and select the correct coefficient

romanna [79]

Answer:

Coefficient of $H^{+}(aq)$ is more than 4

Explanation:

Oxidation: $Sn^{2+}(aq)\rightarrow Sn^{4+}(aq)$

Balance charge: $Sn^{2+}(aq)-2e^{-}\rightarrow Sn^{4+}(aq)$ ......(1)

Reduction: $Cr_{2}O_{7}^{2-}(aq)\rightarrow Cr^{3+}(aq)$

Balance Cr: $Cr_{2}O_{7}^{2-}(aq)\rightarrow 2Cr^{3+}(aq)$
Balance O and H in acidic medium: $Cr_{2}O_{7}^{2-}(aq)+14H^{+}(aq)\rightarrow 2Cr^{3+}(aq)+7H_{2}O(l)$
Balance charge: $Cr_{2}O_{7}^{2-}(aq)+14H^{+}(aq)+6e^{-}\rightarrow 2Cr^{3+}(aq)+7H_{2}O(l)$ .......(2)

$[3\times Equation-(1)]+Equation(2)$ gives balanced equation:

$3Sn^{2+}(aq)+Cr_{2}O_{7}^{2-}(aq)+14H^{+}(aq)\rightarrow 3Sn^{4+}(aq)+2Cr^{3+}(aq)+7H_{2}O(l)$

So coefficient of $H^{+}(aq)$ is more than 4

3 0

2 years ago

A solution has a [oh−] of 1 x 10−12. what is the poh of this solution? 2 7 10 12

Colt1911 [192]

POH = - log [ OH-]

pOH = - log [ 1 x 10⁻¹²]

pOH = 12

8 0

2 years ago

Read 2 more answers

Two 10g blocks, one of copper and one of iron, were heated from 300 K to 400K (a temperature difference of 100 K).

12345 [234]

1) 385 J

2) 450 J

Explanation:

1)

The amount of energy that must be absorbed by a certain substance in order to increase its temperature by $\Delta T$ is given by the equation:

$Q=mC\Delta T$

where

m is the mass of the substance

C is its specific heat capacity

$\Delta T$ is the increase in temperature of the substance

For the block of copper in this problem, we have:

m = 10 g is the mass

$C=0.385 J/gK$ is the specific heat capacity of copper

$\Delta T=400-300 = 100 K$ is the change in temperature

So, the energy absorbed by the block of copper is

$Q=(10)(0.385)(100)=385 J$

2)

Similarly for the block of iron, the energy absorbed by the iron is given by

$Q=mC\Delta T$

where

m is the mass of the block of iron

C is its specific heat capacity of iron

$\Delta T$ is the increase in temperature of the block

Here we have:

m = 10 g is the mass of the block

$C=0.450 J/gK$ is the specific heat capacity of iron

$\Delta T=400-300 = 100 K$ is the change in temperature

So, the energy absorbed by the block of iron is

$Q=(10)(0.450)(100)=450 J$

6 0

2 years ago

List one benefit and one limitation of using scientific models.

Schach [20]

“Models are developed when a scientist’s creativity and insight are combined with data and observations about many similar scenarios”. Models are used for a lot of things in science. As we know everything has advantages and disadvantages, and the same applies to models. Models help us illustrate the concept and formulate hypothesis. When models are used, the scientists are able to notice patterns and develop and revise representation that become a useful model, which makes their scientific knowledge stronger and helps them understand more about the nature of science. Models are a simplified representation. One of the biggest advantages of the model is, that it allows you to have a look at things which are too small such as atoms or too big such as the solar system.

Although, having many benefits, models have quite a number of disadvantages. Models sometimes oversimplify the process therefore leading to a misunderstanding. As models are supposed to be a simplified representation, they will not be complex, which means they will lack detail. For Example “our particle model explains many things about matter, it is not comprehensive — for example, it cannot predict why certain materials have different electrical properties. We could add further refinements that are outside the scope of this course to enable it to do so, but it would make our model so complicated that it would no longer be useful to us”

4 0

2 years ago