Filling 3rd column based on value of 2nd column in data frame in R

I want to check if the 2nd column of my data frame has an empty value or not and fill a third column called "label" accordingly.

Data Frame is like this:

col1   col2   label
hello  there  both filled
this   that   both filled 
start  ""     col2 empty

I am trying this:

for (i in nrow(dataframe)) {

if (isTRUE(dataframe[i,c('col2')] == "") == TRUE) 
   { dataframe[i,]$label <- "both filled" }
else{
   dataframe[i,]$label <- "col2 empty" }
  }
}

But all I get is the same label for every row