What kind of bonds are hydrogen bonds?

During this chemical reaction energy is absorbed. In the chemistry lab, this would be indicated by a decrease in temperature or

Semmy [17]

Reactions like this one absorb energy because the reactants have less potential energy than the products.

<h3>What is an Endothermic reaction?</h3>

This is the type of reaction in which the reactants absorb heat energy from the surroundings to form products.

This brings about a decrease in the temperature as a result of the reactants having less potential energy than the products thereby making option B the most appropriate choice.

Read more about Endothermic reaction here brainly.com/question/6506846

8 0

2 years ago

An igneous rock originally has 3 grams of uranium 238 in it. When dated the rock only contains 1.8 grams. What are the parent an

castortr0y [4]

Answer :

The parent and daughter concentrations (in percentages) is, 60 % and 40 % respectively.

The age of rock is $3.32\times 10^9\text{ years}$

Explanation :

First we have to calculate the parent and daughter concentrations (in percentages).

$\text{Parent concentrations}=\frac{1.8g}{3g}\times 100=60\%$

and,

$\text{Daughter concentrations}=\frac{(3-1.8)g}{3g}\times 100=40\%$

As we know that, the half-life of uranium-238 = $4.5\times 10^9$ years

Now we have to calculate the rate constant, we use the formula :

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{4.5\times 10^9\text{ years}}$

$k=1.54\times 10^{-10}\text{ years}^{-1}$

Now we have to calculate the time passed.

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant = $1.54\times 10^{-10}\text{ years}^{-1}$

t = time passed by the sample = ?

a = initial amount of the reactant = 3 g

a - x = amount left after decay process = 1.8 g

Now put all the given values in above equation, we get

$t=\frac{2.303}{1.54\times 10^{-10}}\log\frac{3}{1.8}$

$t=3.32\times 10^9\text{ years}$

Therefore, the age of rock is $3.32\times 10^9\text{ years}$

5 0

3 years ago

How many valence electrons are in an atom with the electron configuration in example A? Example A: 1s22s22p63s23p64s1 7 1 6 19

Scrat [10]

1 valence electron is the amount

3 0

4 years ago

Read 2 more answers

What is the formula unit for a compound made from Pb4+ and oxygen?

dem82 [27]

Answer : The formula unit of compound will be, $PbO_2$

Explanation :

As we know that one atom of oxygen contains (2-) charge and one atom of lead contains (4+) charge. So, to balance the of charges of lead, the 2 oxygen atoms combine with the 1 lead atom. Thus, the compound formed will be, $PbO_2$ .

That means, when $Pb^{4+}$ combine with oxygen that is, $O^{2-}$ , it gives $PbO_2$ by the criss-cross method.

Criss cross method : It is a method of determining the chemical formula.

The formula unit is a shown below.

7 0

3 years ago

A shiny chunk of metal is found to have a mass of 37.28g. The metal is dropped into a graduated cylinder which contains 20.0 mL

kenny6666 [7]

The density of the material is 2.66 g/mL and it is likely this is made of Aluminum

Explanation:

The first step to know the material of the chunk of metal is to calculate its density. The general formula for density is P (density) = . Moreover, in this case, it is known the mass is 37.28 g, but the volume is not directly provided. However, we know the water in the graduated cylinder had a volume of 20.0 mL and this increased to 34.0 mL when the chunk of metal is added, this means the volume of the metal is 14 mL (34.0 mL - 20.0 mL = 14 mL). Now let's calculate the density:

This means the density of this metal is 2.66 g/mL, which can be rounded as 2. 7 g/mL, and according to the chart, this is the density of aluminum. Therefore, this material of this chunk is aluminum.

7 0

2 years ago