How many protons and neutrons does gallium have?

What is the formula for an ionic compound that forms out of Sr and Br?

lesantik [10]

Answer: St Br2

Explanation: Br has only one valence electrons and Sr has 2 valence electrons this is why we need 2 atoms of Br to for an ionic compound with 1 atom of Sr.

8 0

3 years ago

Which compound has the highest precent composition by mass of strontium?

PilotLPTM [1.2K]

First find the molar masses of all of the compounds:
SrCl2 = 158.53g/mol
SrI2 = 341.43g/mol
SrO = 103.62g/mol
SrS = 119.68g/mo

Then find the molar mass of Sr in each of the compounds. Since there is only one Sr in every compound, the mass will be the same: 87.62g/mol Sr

Now divide the molar mass of Sr by each of compounds' masses:
SrCl2 = (87.62)/(158.53) = 0.553
SrI2 = (87.62)/(341.43) = 0.257
SrO = (87.62)/(103.62) = 0.846
SrS = (87.62)/(119.68) = 0.732

Now multiply each of the results by 100 to get the percent composition of Sr by mass:
(0.553)(100) = 55.3% Sr in SrCl2
(0.257)(100) = 25.7% Sr in SrI2
(0.846)(100) = 84.6% Sr in SrO
(0.732)(100) = 73.2% Sr in SrS

Thus SrO has the highest percent composition by mass of Sr

4 0

3 years ago

Select the correct answer from each drop-down menu.

shtirl [24]

Answer:

A (Hypothesis) is scientific knowledge published through direct observation and remains constant scientific knowledge can change when scientists (generate hypothesis)

7 0

3 years ago

Covalent bonded atoms make up what

White raven [17]

In a covalent bond, the atoms bond by sharing electrons. Covalent bonds usually occur between nonmetals. For example, in water (H2O) each hydrogen (H) and oxygen (O) share a pair of electrons to make a molecule of two hydrogen atoms single bonded to a single oxygen atom.

7 0

3 years ago

Using the following equation 5KNO2+2KMnO4+3H2SO4=5KNO3+2MnSO4+K2SO4+3H20. Starting with 2.47 grams of KNO2 and excess KMnO4 how

Aleonysh [2.5K]

Given equation : $5KNO_{2} + 2KMnO_{4} + 3H_{2}SO_{4}\rightarrow 5KNO_{3} + 2MnSO_{4} + K_{2}SO_{4} + 3H_{2}O$

Given information = 2.47 grams KNO2 and excess KMnO4 and we need to find grams of water (H2O).

Since KMnO4 is in excess, so grams of water(H2O) can be calculated using grams of KNO2 with the help of stoichiometry.

To find grams of water(H2O) from grams of KNO2 , we need to follow three steps.

Step 1. Convert 2.47 grams of KNO2 to moles of KNO2.

$Moles = \frac{grams}{molar mass}$

Molar mass of KNO2 = 85.10 g/mol

$Moles = 2.47 gram KNO2\times \frac{1 mol KNO2}{85.10 gram KNO2}$

Moles = 0.0290 mol KNO2

Step 2. Convert moles of KNO2 to moles of H2O using mole ratio.

Mole ratio are the coefficient present in front of the compound in the balanced equation.

Mole ratio of KNO2 : H2O is 5 : 3 (5 coefficient of KNO2 and 3 coefficient of H2O)

$0.0290 mol KNO2\times \frac{3 mol H2O}{5 mol KNO2}$

Mole = 0.0174 mol H2O

Step 3. Convert mole of H2O to grams of H2O

Grams = Moles X molar mass

Molar mass of H2O = 18.00 g/mol

$Grams = 0.0174 mol H2O\times \frac{18 g H2O}{1 mol H2O}$

Grams of water = 0.313 grams H2O

Summary : The above three steps can also be done in a singe setup as shown below.

$2.47 gram KNO2\times \frac{(1 mol KNO2)}{(85.10 gram KNO2)}\times \frac{(3 mol H2O)}{(5 mol KNO2)}\times \frac{(18.00 gram H2O)}{(1mol H2O)}$

In the above setup similar units get cancelled out and we will get grams of H2O as 0.313 grams water (H2O)

8 0

4 years ago